Ken: My worst week ever but I'd trust Jasper with my life

The Mayor made the admission as he gave his backing to Lee Jasper, the aide who is at the centre of the storm.

Mr Livingstone said he would trust Mr Jasper "with his life" despite the series of allegations that have engulfed his embattled equalities and policing adviser.

"I've been through so much with Lee, way beyond the Greater London Authority. He was absolutely firm about what is right and what is wrong," he said.

"Having been through these last six weeks when he's been the subject of this huge smear campaign from the Standard, that's difficult because it gets to your family. I mean I trust Lee with my life."

The allegations centre on cash granted by the Mayor's London Development Agency to a string of organisations run by friends or associates of Mr Jasper, largely without any results to show for the money spent.

A police investigation into what happened to cash at four of the companies is now under way and there are calls from a cross-party group of MPs for a full inquiry into the affair.

Mr Livingstone insisted in a radio interview that Mr Jasper had not known that his deputy, Rosemary Emodi, had taken a free trip to a £200-a-night Nigerian beach resort and in doing so had broken City Hall rules.

Ms Emodi, who quit her £64,000-ayear post when her trip was exposed this week, went with Errol Walters, director of two organisations linked to Mr Jasper which have received substantial amounts of City Hall cash.

"I was the one that broke the news to Lee ... He was devastated. Rosemary had been his real right hand," Mr Livingstone told BBC London radio.

"We looked at her straight in the eye - well, I didn't but several of my senior staff including Lee did - and said 'the BBC has got these allegations, is there any truth?'.

"They really pressed her, she assured us [there wasn't]. When somebody who you've worked with for eight years - and she delivered, she was one of my most effective officers - says that... We checked. We couldn't find anything."

Mr Livingstone admitted he had found the past few days - starting with his City Hall regime coming under attack from a Channel 4 documentary and ending with the resignation of Ms Emodi - the worst for him personally since he took office eight years ago.

Asked whether he had had a worse week, he replied: "Not since I've been Mayor. I had some worse weeks back in GLC days. This goes on, it comes and goes in waves, and this close to an election the people who don't want you elected pile in."

Speaking today on Radio 4's Today programme, Mr Livingstone defended his senior City Hall aides working on his political campaigns against his rival mayoral candidates Tory Boris Johnson and Lib Dem Brian Paddick. He said it was acceptable for his senior staff paid for by the taxpayer to be involved "providing that they are doing it in their own time and are not using public resources."

The Mayor admitted they were banned from writing speeches or articles for him, even though he has claimed in the past that as long as they were under his name they would be in the clear. He justified his regime's attack on the equalities chief Trevor Phillips, claiming it was down to a legitimate policy difference.

He admitted that City Hall was his personal feifdom adding, "that's what Tony Blair wanted to create".