Police appeal to marathon spectators
The Metropolitan Police says the threat level to London has not changed ahead of Sunday's marathon but has asked spectators to be security conscious.
It says there is no link between the twin explosions in Boston and the London event.
More than 35,000 runners are due to take part in the race.
Chief Superintendent Julia Pendry, Gold Commander for the London Marathon, told the BBC she was confident with current security arrangements.
- From the section UK