Coe warns: Olympics is toughest task ahead

Sebastian Coe has warned Boris Johnson that the London Olympics will be on a "different planet" from any other responsibilities he has as Mayor.

Lord Coe, chairman of the 2012 organising committee, Locog, said the new Mayor should focus his attention on the potential regeneration benefits to London on the Olympic project.

He said: "What I would advise is to understand this is the most complex piece of project management that any mayor will ever have been involved in. This will be on a different planet.

"You are the mayor of a city that has undertaken the most complex piece of work that the city has ever undertaken - the regeneration of 25 per cent of its land."

The mayoral election caused a shift of power on the Olympic board now Mr Johnson joins it, with Olympics minister Tessa Jowell the sole Labour member.

Conservative sources said relations may be strained as Ms Jowell spent the last weeks as the leader of Ken Livingstone's reelection campaign.