Up to 40 men have been forced out of a city by a republican vigilante group who shot dead a father-of-two, it has been claimed.

Andrew Allen was gunned down through a window of his home in Buncrana, Co Donegal, after a group of men tried to break down the front door.

The 24-year-old was from the Top of the Hill area of Waterside, Londonderry, where he was intimidated from about six months ago.

Parish priest Fr Michael Canny claimed a group called Republican Action Against Drugs had become self-appointed executors in the city and were responsible for the attack.

"At some stage last year between the Waterside and Cityside areas as many as 36 or 37 people have been exiled from their community and families," he said. "The people are being exiled because these vigilantes claim they are involved in anti-social activity like breaking into houses and selling drugs.

"They are imposing their law on people as judge and jury and now executor. They have guns and obviously they are prepared to use them."

Fr Cranny believes the victim, whose mother still lives in Derry, is the first of the group of men who fled the city to be shot.

Armed men opened fire on a house on the Links View estate in Buncrana after 9pm on Thursday night. Mr Allen's 34-year-old girlfriend escaped uninjured. A silver Vauxhall Cavalier - registration SJI 2117 - was later found burnt-out in the townland of Ballybone in nearby Fahan, where a second getaway car is believed to have been waiting.

Gardai have appealed for information on anyone acting suspiciously in the area in recent days.

A PSNI spokesman would not confirm claims about Republican Action Against Drugs and said it would not discuss the personal security of individuals. "Where we receive information that a person needs to review their personal security we take steps to inform them," he said. "We never ignore anything that may put an individual at risk."