A man used as "a human bomb" managed to escape unhurt after being forced to drive a van packed with explosives to a Northern Ireland checkpoint, police said on Friday.

"It has all the hallmarks of an Irish Republican Army operation," a police spokesman said after the bomb was defused.The IRA, battling to oust Britain from Northern Ireland, staged three "human bomb" attacks last month. Six British soldiers and the driver of one of the cars were killed in the checkpoint attacks.

In the latest attack, masked gunmen burst into a man's house on Thursday night, locked his elderly parents in the bathroom and took him as a hostage across the border to a derelict house in the Irish Republic, police said.

He was then forced to drive back across the border in a van packed with 1,100 pounds of explosives.

He was told by the gunmen to take the van to the checkpoint and shout a warning. The bomb was fitted with a five-minute timer, they said.

The man escaped, the detonator exploded but the main charge failed to go off. No soldiers were hurt in the attack.