An ex-aide to Labour mayor candidate Frank Dobson's running mate has admitted making the complaint that led to Ken Livingstone's censure for not properly registering his earnings from journalism and public speaking.

Rob Smeath, a Labour activist and treasurer of Trevor Phillips's mayoral campaign - which the broadcaster gave up when he decided to run as Mr Dobson's deputy - insisted he had acted on his own initiative.

Mr Livingstone, the independent candidate for London mayor, had complained he was the victim of a "dirty tricks" campaign after mystery surrounded who had complained to the Labour-dominated Commons Standards and Privileges Committee.

The committee had received a letter from a Loughborough University research student John C. Jones asking them to investigate Mr Livingstone's earnings. Mr Jones, however, denied having had anything to do with the matter.

But it has now emerged that Mr Smeath, a lawyer, attempted to hide his complaint by getting Mr Jones to send the letter.

Trevor knew nothing - Smeath

He admitted to the London Evening Standard newspaper that he had orchestrated the letter of complaint to the committee.

"I wanted to get the issue of MPs not declaring earnings discussed. I was so incensed," he said.

"I had been involved in the Trevor Phillips campaign and I wanted to be distanced from any idea that Trevor was making me do this."

Mr Smeath said that he had asked Mr Jones if the letter could be sent in his name as the student was "absolutely disinterested" in politics and therefore seemed the perfect person.

He said that Mr Jones agreed "albeit reluctantly". But when journalists tracked him down earlier this week, he denied responsibility because he thought: "Why have I got caught up in this?"

'Millbank Tendency'

This is the second time Labour supporters backing Mr Dobson, though not directly connected with his camp, have worked to de-rail the campaign former health secretary's chief rival.

Earlier this month BBC News Online revealed an attempt had been made to pack the audience of the BBC's Question Time programme, on which both men appeared, with Dobson supporters instructed to "clap, jeer and cheer in the right points".

Responding to the news, Mr Livingstone said: "We knew that it was organised by someone of the 'Millbank Tendency'."

"We were just surprised that it was someone so close to Trevor and Frank. There will be lots more dirty tricks but I don't think the public is drawn in."

Mr Livingstone said of the Standards Committee report: "I was told about the report the night before but no-one asked to see me or to ask about my views.

"Without seeing the person that they are investigating it is just bizarre.

"When I got home my partner said: 'If you are earning so much money how come we are always in debt?'"

'Dirty tricks'

He continued saying: "In a year the company may have an income of �98,000 through public appearances and talks. �53,000 is invested in employing people, paying them and on items like computers.

"Then we are left with a company profit of just about �50,000 and a lot of tax before spending on any campaign."

Later, the Brent East MP said: "Frank Dobson started his campaign by asserting that he intended to focus on policy not personalities."

"However, it appears that the first major step by some of his supporters has been to launch dirty tricks operations against other candidates."

"These serve merely to divert attention from policies - of which by far the most important is how to improve the public transport system."

A spokeswoman for Mr Dobson declined to comment on Mr Smeath's actions, but insisted it was "getting ridiculous that we are looking at the whistleblower rather than the person who broke the rules".