Gordon Brown was yesterday handed the findings of an independent review into claims that intelligence forces were monitoring mobile phone calls made by the Omagh bombers.

The Prime Minister ordered Sir Peter Gibson, the Intelligence Services Commissioner, to examine all intercept material and how it was shared after relatives gave the Government a one-week deadline to hand over the information held by the Cheltenham-based listening station in September.

It followed a BBC documentary that revealed GCHQ was recording the bombers' calls before the blast which killed 29 people.

Mr Brown is expected to make a formal statement on the report early next year.

Shaun Woodward, Secretary of State Northern Ireland, said: “I confirm that the Prime Minister has received Sir Peter Gibson’s review of intercept intelligence material available to the security and intelligence agencies in relation to the Omagh bombing, and how any material was shared.

“As the Prime Minister made clear when Sir Peter Gibson was asked to carry out his review, a statement to parliament will be made as soon as possible after the Government considers the report.” It comes as the Police Ombudsman failed to uncover who phoned the warning that a gun and mortar attack would be mounted in the town two weeks before the 1998 bombing, the worst atrocity of the Troubles.

Despite a 12-month investigation, relatives have been told the identity of the caller remains unknown.

It has been suggested the call from a phone box in Beragh, about 10 miles from Omagh, was made by a serving police officer at the time, but no evidence has been uncovered to support the report.

Although various Real IRA figures are behind bars, no one has been convicted of the Omagh murders. In December, a south Armagh man was acquitted of the killings, with the judge criticising police evidence.