David Cameron has described the conduct of Ken Livingstone's administration as "completely unacceptable".

Speaking at prime minister's questions in the Commons on Wednesday, the Conservative leader challenged Gordon Brown to condemn the actions of the London mayor and his staff.

The clash came after Lee Jasper, the Labour mayor's race adviser, resigned following fresh allegations about his conduct in relation to beneficiaries of taxpayers' money.

Jasper had already been suspended on full pay after inviting a police investigation, but quit the post after a failure to declare a flirtatious relationship with a woman connected to two organisations that had benefited from mayoral grants emerged.
 
Cameron told MPs that "six police investigations are now underway" into affairs at City Hall.

He asked Brown to condemn the channelling of funds "into organisations run by friends and cronies" of Jasper.

However the prime minister insisted that he would not comment on an ongoing police inquiry.

"It is not a matter for this House until the police complete their investigation," Brown said.

The Tory leader also reported that Livingstone had said he would "trust Lee Jasper with his life... and last night he said he was already planning to reappoint him".

But Brown responded with an attack on the Conservative candidate for mayor on May's election, Boris Johnson.

"If he wishes to support policing in London, why does his candidate for London mayor say that his first targets for cuts will be transport and policing?" he asked.