Three people had been killed by republican dissidents within 48 hours. It was the morning after the third victim, a policeman, had been shot dead in Craigavon. The Special Branch officer spoke politely, but with determination, to south Armagh man Martin Winters.

"He said to me, 'Martin, we meet again. But we've bodies on the streets now haven't we? It's not on, Martin. If you'd met us and cooperated before, none of this would have happened. We could have put this man 'X' away.'"

'X' is a Real IRA leader, originally from south Armagh, but who now lives in the Republic. Winters knows him. But the offer that followed, he says, stunned him – a six-figure sum and a home abroad if he provided the security forces with enough information to arrest, convict, and imprison X for life, and thus help close down the Real IRA.

The security services regard Winters (58) as a senior Real IRA figure, a claim he denies. The Sunday Tribune meets him at a location near Dundalk, Co Louth. He's extremely nervous. Although he lives in Newry, he refuses to meet in the North because he believes the briefcase he's carrying would be seized by the security forces there. He empties the contents onto a table.

There's a brown envelope containing £1,000 in £20 notes which, he says, he was given as "a taster". Then, a scrap of paper with the telephone number of an alleged intelligence officer; and another note with contact details relating to an apparent MI5/Special Branch/FBI attempt to recruit him as an informer in the US.

But that's not all. He lifts out two devices that appear to be electronic tracking and listening equipment which were attached to his car. It's a tale which spans five years and two continents.

If Winters' account is true, the security services have been attempting to set up an operation, employing considerable resources, to "put away" X in the same manner they dealt with former Real IRA leader Mickey McKevitt. FBI-MI5 agent Dave Rupert received several million pounds and a new identity for providing information which led to McKevitt's imprisonment for directing terrorism.

Winters has logged the security forces' reported approaches with his solicitor. "I'll go to court to get them to leave me and my family alone. I want them to stop offering me money and to stop bugging my car. I don't want to work for them, and I never will."

Winters says he has no convictions, has never even been arrested, and is "not a member of any political or military group". His relationship with X and X's family is based solely on the friendship of growing up in the same area, he claims.

The security forces reportedly began pursuing him to work as an agent five years ago. He was stopped at a Newry checkpoint by two Police Service of Northern Ireland (PSNI) Special Branch officers.

'We want to talk'

"I offered my licence. They laughed and said, 'Martin we don't want your licence, we want to talk. We know you're highly placed in the Real IRA and you know X. But you're a family man too. If you work for us, you'll never have to work again. We'll look after you and your family.'

"They knew I visited America and suggested we meet there, or in Belfast or Dublin, as I might be uncomfortable meeting them near home." Winters says they threw a scrap of paper into his car with a telephone number, which he later found out was that of Newry's Ardmore police station. X was in jail at the time but wasn't serving a long sentence. Winters told X's family what had happened.

The second attempt to recruit him as a spy was in November 2006 in New York's JFK airport, he says, when he was visiting friends. "Going through customs, my luggage was searched in great detail. Then, a policeman persisted in 'showing' me the way out of the airport. He took me to a small office instead. Inside, were two well-dressed boys in shirts and ties with American accents. They introduced themselves as FBI and told me to sit down.

"'You and X are up to your necks in the Real IRA,' they said. 'We don't like terrorism since 11 September. We could throw you in jail for 15 years. But that won't happen if you cooperate. There are other people who want to talk to you.'" Winters says the two Special Branch officers, who had previously approached him in Newry, then entered the room. They were men in their 30s and 40s.

"They said, 'Have you thought about our offer? Do you want to see the Troubles coming back and bodies on the street, Martin? We've families, you've a family. It's not you we're interested in, it's X. If you work for us and help put X away for good we'll look after you. You'll want for nothing.'"

'I know nothing'

A woman in her late 20s then entered the room, Winters claims, and was introduced as MI5. She repeated the offer. "I said, 'I know nothing. I've never been involved in anything,' and they all started laughing. I asked if I was under arrest and needed a solicitor. They said I wasn't. I tried to reach for my passport, which was on the table, but one FBI boy put his hand on it.

"'Just stay a few minutes,' he said. 'You've had a seven-hour flight. You've been held by customs and by us for three hours. You must have jet lag. Get a good rest tonight and meet us tomorrow at 12pm. If you don't, we'll make your three-week stay hell.'"

Winters shows the Sunday Tribune a piece of paper with the address where he was allegedly asked to go: a restaurant in Lakewood, New Jersey. A contact telephone number is also included.

He neither turned up nor telephoned. He was followed throughout the trip "into bars, restaurants, shops – everywhere" by men he believes were FBI. There was no attempt to detain him on his journey home. However, in May 2007, US immigration at Dublin airport prevented him boarding a flight to New York. He says no reason was given.

Last August, he says, he was driving his car when he heard a rattle. "I got under the car, thinking the exhaust was loose but it was fine. Then, I noticed something with wires coming out of it hidden under the bumper. There were two pieces of equipment which, he believes, were listening and tracking devices.

The Sunday Tribune asked a security expert, with a British military background, who now specialises in electronic surveillance, to examine photographs of the devices. He was unsure what the smaller one was but he described the larger item, which is wrapped in black tape, as "an extremely viable piece of surveillance equipment" which appears to have military origins.

"The plug-like shape in the middle is a GPS (global positioning satellite) receiver which connects with satellites in the sky to pinpoint a vehicle's location. Those who planted this device would be able to log onto the internet and track the car's movements on their pc. The movements could be logged up to every 10 seconds," he says.

"There are six HP7 batteries at the bottom to power the unit. At the top is what seems to be a mobile-phone aerial and also a piece of wire which would have been attached to a microphone. The microphone would pick up conversations in the car.

"I believe there's a Sim card buried inside this unit. Whoever planted it could ring the Sim number and listen to what was being said in the car." The security expert said a smaller, more sophisticated device, "the size of a slimline mobile phone" – without batteries because it would run off the car's battery – could have been planted but that would have needed 15 minutes working on the vehicle without being spotted. Whereas the equipment in the photograph could have been fitted in seconds.

On 7 March, the Real IRA shot dead two British soldiers at Massereene. On 9 March, the Continuity IRA murdered Constable Stephen Carroll in Craigavon. The following day, Winters was driving from Newry to a Belfast garage to have his car serviced. One of his three grown-up sons was in the passenger seat.

He was stopped by an unmarked police car outside Banbridge, Co Down. "They said I'd committed a motoring offence. I said I hadn't. Then, a marked police car appeared. I was asked to get out of my vehicle and into the marked car to view my traffic offence on a camera."

Winters says there was no camera. One of the Special Branch men, who had twice attempted to recruit him, appeared and made another offer. But another police officer was agitated. "He says to the Special Branch boy talking to me, 'You're wasting your time with him. He'll never work for you. Just take him and X and blow them away.'"

The Special Branch officer then apologised to Winters. "He said, 'Ignore my colleague. He's emotional because he was a good mate of Constable Carroll's.'" Then, a black man in his late 30s with an English accent, sitting in the back of the car, introduced himself as an MI5 officer.

A six-figure sum

"He says, 'Martin we'll give you a six-figure sum, we'll buy you a house in America or anywhere you want in the world. We'll set you up for life. We'll give you £5,000 even if you meet us for one hour. Just listen to what we have to say and, at the end, you can walk off with the money and do nothing if you want'." Winters claims he was told his exclusion from the US could be immediately reversed.

Winters says he was held in the marked car for 15 minutes. "The Special Branch boy then put a brown envelope into the top pocket of my leather jacket. He says 'Here's a few pounds to have a drink and think things over.'" Winters later opened the envelope which contained £1,000 and a mobile telephone number for 'Mark'.

The police and MI5 officers were courteous in their contact with Winters, he claims, except for one veiled threat from a Special Branch officer. "He said, 'if you don't cooperate, your sons could be set up'." Winters says he's giving the £1,000 to Newry hospice.

The Sunday Tribune phones Mark's mobile on Friday afternoon: "Is that Mark? This is the Sunday Tribune newspaper. We've been given this number by a man called Martin Winters who says you're trying to recruit him to work for the intelligence services."

A well-mannered English voice on the other end says: "I think you've got the wrong number," and hangs up. Every time we tried to ring again, the phone automatically went onto voicemail. We left a message. He didn't return our call.