Police in Northern Ireland guarding a military helicopter crash site were attacked on Monday night by what are thought to have been nationalist youths, it has been revealed.

The helicopter crashed at Crossmaglen, south Armagh on Sunday, leaving six people, two airmen and four police officers, injured.

Police who were guarding the wreckage are believed to have come under attack from petrol bombs and other missiles.

The previous day, ambulance crew were pelted with stones, fireworks and snowballs while tending to the injured and an ambulance taking one of the injured men to hospital was ambushed.

"They stopped the vehicle for about a minute and shone torches into it," commented the Ambulance Service's director of operations, Brian McNeill.

"We are only trying to do our job and it is difficult enough going to a major incident like that without having to deal with unruly crowds, and it is unacceptable."

A pair of police vehicles were damaged in the Monday attacks but nobody is believed to have been injured.