The response of most God-fearing mortals who discover a rusty unexploded second world war bomb in a field would be to retire to a safe distance and dial the emergency services. But then most people are not father-of-three David McDaid.

Rather than head for a sandbag bunker when he found a 500lb German bomb on a farm in Donegal, McDaid loaded the Nazi projectile on to a tractor trailer, photographed it in his girlfriend's garage and put it up for sale on a website. It was only when customers were browsing the DoneDeal.ie site, where McDaid had placed an advert under the description "World War II bomb for sale", that gardaí were alerted.

McDaid (36), who had posted his advert last Monday and found the authorities on his doorstep 24 hours later, said: "It was like the D-Day landings. I posted this bomb on the website and the next day a whole army platoon was at my door. It was like something you'd see in the films. There were about 15 soldiers dressed in the full gear, two jeeps and a lorry."

The corroded device is believed to have been on board a German bomber which crashed near Glengad in northern Donegal. It lay around until the early 1990s before McDaid collected the bomb and kept it in a shed at his partner Breege Doherty's home before deciding to sell it.

DoneDeal.ie said: "When we were informed of the bomb we alerted the authorities immediately. Mr McDaid broke our terms and conditions and he has had his account with us terminated."