The previously unknown Irish Republican Liberation Army claimed last night that it shot an officer who was ambushed in Dungannon, Co Tyrone.

A man and woman have been arrested and questioned about the shooting, the second of its type in five days. Last week an off-duty officer was shot outside his son's school in Londonderry.

A statement by the IRLA said: "There is now a central command within our organisation. More shootings will follow. We again reiterate our threat to Sinn Feiners in north Belfast. We again demand they resign from local DPPs' boards."

The injured policeman, Paul Musgrave, was shot in the shoulder. He is said to be in a stable condition.

He had just left work on Monday when his vehicle, believed to be a 4x4, was targeted close to a Catholic church in the town.

Mr Musgrave, who is in his 30s, was able to drive to safety in the nearby Dungannon police station and was then taken by ambulance to Craigavon Area Hospital.

Chief Constable Sir Hugh Orde said his officers will not be deterred from carrying out their duties. Those behind the attack had taken cowardice to new levels, he claimed.

Sir Hugh said: "This will not deter police officers going about their day-to-day duties of protecting communities in Northern Ireland. "We will continue to carry out our duties as fairly and properly as we can.

"It makes it all the more impressive, what has been achieved by the PSNI over the last five years.

"They have pushed edges continually.

"If a small number of disenfranchised people, who have been clearly rejected by their community as stated by every political leader wish to continue, we will pursue them to the ends of the earth."