Petrol bombs were thrown at police vehicles as officers investigated a suspect device in Northern Ireland, authorities said.

Army bomb disposal experts later disabled an improvised explosive device, which police claimed was the New IRA (Irish Republican Army) was responsible for.

The operation in Creggan, in Derry/Londonderry, started on Monday morning and involved 80 officers and explosive detection dogs. It came after a mortar device was found on Saturday morning in Strabane, about 24 km south of Derry/Londonderry.

"Following a large scale search operation in the Creggan area of Derry/Londonderry, police located a suspect device in a parked vehicle," said a press release on Tuesday.

"A clearance operation was commenced with a number of families being asked to leave their homes for their own safety.

"During the operation, a crowd of 60-100 persons gathered, some of whom attacked police vehicles with missiles and over 40 petrol bombs."

Police said that at least two young people sustained injuries when they tried to throw petrol bombs at the police cordon. No officers were injured during the attack.

"It is our assessment that the New IRA is responsible for this bomb. The bomb would have killed or maimed anyone near it when it detonated," said the police statement.

"Whilst it is [the] clear intention of the New IRA to murder community police officers trying to keep the community of Derry/Londonderry safe, it is also very clear that the NIRA has a total disregard for the lives of everyone living in Creggan."

Authorities also announced that it had released a 33-year-old man arrested under terrorism legislation in connection with the improvised explosive device in Strabane.

Police said they would remain in the area to carry out further investigations.

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