A warning stating a device would detonate at the Park Lane hotel within 10 minutes was received by the Daily Mail newspaper at 1155 BST.

The newspaper notified Scotland Yard which immediately sent three officers to investigate, but they were not able to evacuate the building before the bomb exploded at 1218 BST.

Police worked quickly to clear the area after the explosion fearing there could be another device nearby.

The blast caused extensive damage to the hotel and neighbouring shops with broken glass spread over a wide area.

Witnesses said police arrived only five minutes before the bomb went off, and it is not clear whether the hotel was warned before they turned up.

A spokesman for the Metropolitan Police said an officer telephoned the Hilton shortly after receiving the warning, but the hotel denied this.

"A policeman was just telling the assistant manager that he had better evacuate when the bomb went off," said press officer Anne Crewdson.