SENSATIONAL allegations that the SAS operated an undercover death squad in Northern Ireland in 1971 and 1972, which killed some 30 members of the IRA, are contained in a 280-page book published yesterday. If true, it would rewrite the history of the current troubles. The problem is that the way it is written leaves grounds for doubt.

The author of The Nemesis File* is a former member of the SAS writing under the pseudonym Paul Bruce. The book is named after the alleged code name used for the covert operation under which the executions took place. Bruce also claims that innocent young Catholic men were picked up at random off the streets of Belfast by his SAS unit and killed as part of a British Government campaign to foment a real sectarian war between Catholics and Protestants. The hope was the two sides would tear each other apart, allowing the politicians to put the pieces together afterwards, he said.

The Ministry of Defence, which only received the book yesterday, is taking the allegations seriously, given the delicate state of the Northern Ireland peace process, and the gravity of the allegations. ``British forces operate within the law and the behaviour of any members is something for which they can be held accountable in law,'' a spokesman said. ``If the author has any information that should be placed before the authorities, he should have done so long before now, and it could be a matter of proper inquiry.''

The MoD view is that although the book does not give dates and is generally vague about places, it should not be dismissed lightly as yet another Christmas offering about the SAS, the second within a week.

The author, a stocky, middle-aged man with attitude, turned up at the book's launch in London wearing a ski mask to hide his face. He insisted his story was true, but refused to reveal corroborating details, claiming he was afraid of the IRA and had received death threats.

The two sites, near the border with the Republic, where he says the bodies are buried, are off Blackskull Road between Dromore and Lurgan, map reference 534160, and in Tardree Forest, Antrim, map reference 925182.

Bruce said he had only been 23 at the time, ``a keen young soldier proud to be in the SAS'', to which he had been transferred from the REME. ``We killed people we were told were members of the IRA,'' he added. ``It was a thankless, horrible task and if I had had any idea I would have ended up doing that kind of thing I would never have joined the Army, let alone volunteered for the SAS.''

The men the four-soldier unit killed were handed over to them at the border with the Republic by another SAS unit, he said. He thought they had been brought from the Republic by MI6 agents. They were not told the prisoners' names, and they led them to believe they were being taken to the RUC for questioning, not to their deaths. The unit had worked in casual clothes - leather jackets, jeans and Chelsea boots - not in uniform, he added.

At one point he decided some of the prisoners may have been drugged before being handed over by MI6, because they seemed ``kind of zombified'' and proved very docile. ``All in all, this was pretty boring,'' he added chillingly. He described how one of his colleagues messed up a killing, shooting the man in the neck, not the back of his head, and he had to finish the job because the man was lying screaming with his jaw shot off.

He denied he had murdered anyone. ``I fought a war against the IRA,'' he said. ``It was tit for tat.'' When it was pointed out their actions were contrary to the rules of engagement under which British troops in Ulster operated, he replied angrily: ``Balls to the rules of engagement. We were the SAS. We do not fight under rules of engagement. We are talking about 20 years ago, and I thought the IRA were the enemy. I never killed women or children. I was just a tool. I was being used by the British Government. I was just told this is what you are going to do.''

Asked how many people he had executed he got upset. ``I did not execute anybody,'' he said. ``I killed IRA soldiers. I will not tolerate this bullshit. Do you realise how many people we saved? I am a nice guy. Of course I regret what I have done, but I was carrying out orders. We were told these people had to be killed and we did it.''

The first two men he killed were suspected terrorists gunned down in West Belfast outside a shop where they had been buying cigarettes. The next man was a suspect they picked up through an informer called Yvonne. It was after that with the other three, identified as Benny, JR, and Don, that they began to kill men brought to them for execution by MI6.

He said he had left the Army in October 1972, and that Don, his unit commander, had been killed in the Falklands war. He was not breaking the Official Secrets Act because that only applied for 20 years, he said. He insisted his publisher, John Blake, had been given proof of his identity and the authenticity of his claims, including an affidavit from a former colleague.

Mr Blake said they had his Army number and his SAS medals, and confirmed the affidavit's existence. Bruce had also shown them the sites where he claims the bodies are buried, although they had not done any digging, he said. That was for the authorities to do. ``We checked him in every way,'' he added. ``He is angry. He is not interested in money. He just wants people to know what he was forced to do.'' Although Bruce originally claimed to have killed some 40 men, the publishers checked through each alleged incident and decided it was nearer 30.

Bruce had been warned by his lawyer of the consequences he could face if his charges proved true, he added. As for money, his advance was #3000, he had not asked for more. He would, however, receive royalties if it sold. The first hard-back print run is of 60,000 copies.

* The Nemesis File by Paul Bruce; Blake Publishing Ltd, #15.99