IRA bomb threat at all-time high

Scotland Yard and the security services last night issued a stark warning that the threat of another IRA attack, particularly on mainland Britain, has never been higher.

Security sources in Northern Ireland confirmed yesterday that the RUC and the Army have been alerted about the threat of new terrorist attacks. As part of new safeguards, personal protection has been strengthened for a number of public figures in the province.

RUC officers in Belfast believe that 10 tonnes of home-made explosives discovered in London last month were destined for use in attacks on mainland targets to coincide with the IRA bombing of the Army's Northern Ireland HQ at Lisburn, Co Antrim, earlier this month.

Republican terrorists are thought to be determined to avenge last month's fatal shooting by police of their London operative, Diarmuid O'Neill. They might also wish to mark one of a number of upcoming significant dates, including the presidential elections in the US and several anniversaries in the Provisionals' calendar, with a "spectacular" attack.

A Scotland Yard source said this view was backed by information gathered by MI5 and police intelligence experts: "The threat has never been higher. We think it is the highest is has been since the end of the ceasefire." Assistant commissioner David Veness, head of Scotland Yard's specialist operations, speaking on the record, said: "Looking at the period ahead, we are entering dangerous months. I regret that the threat is likely to be in the long term."

And a security source added: "There's felt to be a heightened threat at the moment."

While the alert is understood to be based on collated intelligence rather than on a single piece of information, the strength of the warnings, both on and off the record, emphasises the seriousness of the threat.

The Metropolitan police will introduce a series of anti-terrorist measures in London in the run-up to Christmas

These will include an increase in the number of officers involved in anti-terrorism activities and extra patrols and searches of suspicious premises and property. Officers will mount extra road-blocks in the capital and undercover operations will be stepped up.