McGlinchey was until recently a strong Sinn Fein supporter. Sources said he was instrumental in organising meetings in south Derry of republicans who believe SF shouldn't sign up to policing.

The Provisionals face huge problems in south Derry. In the summer, local IRA units broke away from the organisation because of disillusionment with the leadership. It is the most serious division in republican ranks since the split that led to the Real IRA's formation in 1997.

The Provisionals say disgruntled members from other areas, including Belfast, are linking up with the south Derry men and attempting to form "another army". They claim this is a serious threat to the authority of their leadership.

Last week, around 250 people attended an anti-Agreement republican meeting on policing in west Belfast. Sinn Fein representative Declan Kearney, who was among the speakers, met substantial opposition when he voiced Sinn Fein policy.

Republican sources told the Sunday Tribune that the Provisional IRA had visited some former supporters and told them "these meetings must be knocked on the head".

Meanwhile, a veteran Co Antrim republican has resigned from the party over policing. Laurence O'Neill from Glenravel told the Sunday Tribune that his "outspoken criticism of Sinn Fein policy on policing" meant he could no longer remain in the party.

"I'm a lifelong republican but I firmly believe no republican can ever sign up to policing and that has led to a fallout with former friends, " he said.

O'Neill was sentenced to 15 years for weapons possession in the early 1970s. He is known as a prolific fundraiser and is said to have already raised �?£10,000 for Sinn Fein's next election campaign.

Sources said a Sinn Fein representative had visited O'Neill, reprimanding him for attending a meeting in Toome.

He had also been told not to attend last week's meeting on policing in west Belfast.

A prominent west Belfast republican has also voiced strong opposition to the Sinn Fein leadership and disclosed that he has resigned from the Provisional movement. Tony Catney, a former ard comhairle member and senior electoral strategist, ran the Sinn Fein office in Brussels in the mid-'90s and is also an ex-head of the POW department.

In a letter in yesterday's Irish News, Catney rejected allegations being circulated by senior Sinn Fein members that he had formed a new military organisation. "I was a member of the republican movement for 37 years and resigned last year as a result of the lack of internal debate on matters of policy and strategy and the manner in which membership were expected to blindly follow a leadership-led policy without question or dissent, " he wrote.