A CODED bomb threat from Irish terrorists sparked major security scares near Buckingham Palace on the eve of the Queen’s historic visit to the republic.

A controlled explosion was carried out on a suitcase abandoned outside a hotel and streets around the Mall were shut off for five hours after the warning from Irish republican dissidents.

The caller triggered high alert across central London after telling authorities last night that a bomb was planted in a “non-specific” part of the capital.

A police statement said: “A bomb threat warning has been received relating to central London today.

“The threat is not specific in relation to location or time. Policing operations and contingency planning remain under constant review and a wide range of overt and covert tactics will continue to be used in London.

“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 to the confidential anti-terrorist hotline on 0800 789 321. In the event of an emergency, always dial 999.’’

Roads around the Admiralty Arch area of The Mall were reopened before noon after the area’s drains were understood to have been searched.

Roads were closed around the ceremonial gateway leading from the corner of Trafalgar Square when an officer spotted “something suspicious’’ at 4.20am.

A controlled explosion of a suitcase outside a hotel was carried out in nearby Northumberland Avenue as officers attended to suspicious packages.

The alerts came as the largest security operation in the history of the Republic of Ireland swung into action amid fears dissident republicans will try to disrupt the Queen’s momentous trip.

Armed British police officers will patrol Irish streets alongside thousands of gardai and soldiers to protect the 85-year-old and the Duke of Edinburgh as they travel around the republic.