A booby-trap device exploded under the policeman's car on Monday night as he drove through the village of Spamount, near Castlederg, County Tyrone, on his way to start night duty.

Members of the public who dragged the injured officer from his burning car were hailed for their actions and Chief Constable Sir Hugh Orde said he could not thank them enough. The policeman suffered serious leg injuries but, after undergoing emergency surgery, his condition was said not to be life-threatening.

The finger of blame was pointed at dissident republicans opposed to the peace process - they were responsible for gun attacks against two PSNI officers in the county last November in Dungannon and Strabane - and a pipe bomb attack on a police station.

Sir Hugh said the fingers were pointed in "entirely the right direction".

The Chief Constable said: "This was another attack by a group trying to unravel everything that has been achieved. They have not defeated the police service for the last 38 years and if they seriously think this sort of event is going to defeat the PSNI they are badly mistaken."

Sir Hugh said the threat from dissidents remained high because they were in their "end game".

"Very clear messages have been sent out by everybody. Every political party has signed up to policing, everyone wants to move on. We had a major investment conference last week - this place is moving in the right direction and I think these people realise that.

"They are out of date, out of time, and they are lashing out at an easy target, an easy target which will give them some sort of publicity.

"It will not put my officers off delivering community policing and it will not deter every member of the community who is in their right mind from working with us to deliver a safer Northern Ireland."