Members of an Army unit dubbed Britain's secret terror force have admitted breaking the law by firing on unarmed IRA suspects in west Belfast.

The Military Reaction Force (MRF) also carried out drive-by shootings of nationalists 40 years ago, even though there was no independent evidence any of them were members of the republican group, a new television documentary has claimed.

The elite soldiers believed military regulations prohibiting firing unless their lives were in immediate danger did not apply to them.

One told the BBC's Panorama programme: "We were not there to act like an Army unit, we were there to act like a terror group.

"We were there in a position to go after IRA and kill them when we found them."

Northern Ireland's attorney general John Larkin QC, chief legal adviser to Stormont's powersharing ministerial executive, has faced criticism after floating the possibility of ending prosecutions for Troubles-related killings.

More than 3,000 deaths are being investigated by detectives from the Historical Enquiries Team (HET) as part of the peace process.

The most notorious unjustified Army killings happened at Bloody Sunday in Derry in 1972, when soldiers opened fire on innocent civil rights protesters.

The reaction force had around 40 hand-picked men from across the British Army who addressed each other by first name and dispensed with ranks and identification tags.

They operated at the height of the Northern Ireland conflict early in the 1970s, when bombings and shootings by paramilitaries happened almost daily.

Another ex-member said it was part of his mission to draw out the IRA and minimise its activities.

"If they needed shooting they'd be shot," he said.

The Army has a series of rules known as the Yellow Card, which guides when a soldier can open fire lawfully.

Generally, lethal force was only lawful when the lives of members of the security forces or others were in immediate danger.

Another soldier said: "If you had a player who was a well-known shooter who carried out quite a lot of assassinations... it would have been very simple, he had to be taken out."

According to the Panorama programme, to be broadcast tonight, seven former members of the force believed the Yellow Card did not apply to them and one described it as a "fuzzy red line", meaning they acted as they saw fit.

Some said they would shoot unarmed targets.

The MRF's records have been destroyed but the soldiers denied they were part of a death or assassination squad.

Tony Le Tissier, a major in the Royal Military Police, said: "They were playing at being bandits, they were meant to be sort of IRA outlaws.

"They were playing at being bandits, they were meant to be sort of IRA outlaws.

"That's why they were in plain clothes, operating plain vehicles and using a Thompson sub machine gun (favoured by the IRA)."

In the early 1970s, nationalists would man barricades in west Belfast aimed at preventing troops from entering.

Some soldiers said they would drive by and open fire, even if they did not see anybody brandishing a gun.

Among those they killed, in May 1972, were father-of-six Patrick McVeigh.

His daughter Patricia said: "We want the truth.

"We don't want to stop until we get the truth."

Many relatives of people killed during the conflict by republican and loyalist paramilitaries and state forces have expressed outrage at the suggestion by the attorney general that those perpetrators yet to be caught should not face justice.

The legal figure also advocated ruling out further inquests and inquiries into the crimes committed during the 30-year conflict, insisting a line should be drawn on offences perpetrated before the signing of the 1998 Good Friday peace agreement.

During Prime Minister's Questions in the Commons, Mr Cameron made clear the Government had no plans to legislate on any form of amnesty.

Panorama: Britain's Secret Terror Force is on BBC One at 9pm tonight.

By Michael McHugh, Press Association

PA Media