2001: Second blast at London post office
A bomb has exploded at a north London postal sorting office. It is the second such attack in three weeks and has been linked to the Real IRA.
One passer-by - a man in his 20s - was slightly injured in the explosion in Hendon at 0153 BST.
After the attack, the head of Scotland Yard's anti-terrorist branch, Deputy Assistant Commissioner Alan Fry, told reporters dissident republicans from Northern Ireland may be planning a bombing campaign ahead of the general election.
Mr Fry said police had contingency plans for dealing with the "major challenge" of a terror campaign ahead of the election, which is expected to be called within days.
"We have seen sustained activity in election campaigns both in '97 and '92," he said. "We take note of that and we will be doing everything possible to secure the safety of those taking part in the election and the general public."
A spokesman for Scotland Yard said no warning was given ahead of the latest blast and no-one has admitted carrying out the attack.
But Mr Fry said: "The most likely dissident group to be responsible was the Real IRA in view of their on-going terror campaign in Northern Ireland and London."
Last month, a device exploded on the steps of the Hendon sorting office but no-one was hurt.
In the past year the capital has been hit by several bombings blamed on the terrorist group. These include the bombing of BBC Television Centre, a rocket attack on MI6's headquarters and an explosion on Hammersmith Bridge.