Bomb threat to London from Irish dissidents

Parts of central London, including roads around Buckingham Palace, were sealed off yesterday after a bomb threat by dissident republicans on the eve of the Queen's visit to Ireland.

The warning, received by police in Northern Ireland and Scotland Yard on Sunday evening, contained a recognised code but did not point towards any specific locations where an attack may take place. Streets in the capital were temporarily shut down during the alert. The Mall was closed after the discovery of a disturbed manhole cover and Carlton House Terrace was cordoned off after a break-in at a building where a Government think-tank is situated.

An abandoned bag was also blown up in a controlled explosion on Northumberland Avenue.

But the threat level from dissident groups has not been raised, staying at "substantial" – lower than the overall danger to the UK from Islamist terrorists, which is "severe" and indicates an attempted attack is likely to take place.

Security sources said the use of a code word in the warning meant it had to be taken seriously, but the lack of information about targeted areas pointed towards an attempt to cause disruption rather than a bombing.

The dissident republicans, it is believed, want to avoid "another Omagh", the indiscriminate slaughter of civilians, while continuing to hit what they claim are legitimate targets such as the police, the armed forces and Government officials.

Scotland Yard officers were working with the City of London and British Transport Police, a police statement said. It said: "At this time Londoners should continue to go about their business as usual but we encourage the public to remain vigilant and report any information about unusual activity or behaviour which may be terrorist-related."

The largest security operation in the history of the Irish Republic is currently under way for the royal visit, with armed officers from the UK carrying out patrols alongside their colleagues from the Garda.