Mayor probed after campaign cash claims

The Electoral Commission told the Standard it was checking allegations that Mr Livingstone had not complied with the law on donations. He has not declared a single personal donation in the past seven years, claiming any money he spends is raised by the Labour Party nationally.

Labour says it tells all potential donors they cannot give money directly to the Mayor and have to give it to the party HQ instead. But it has emerged that Mr Livingstone's own website asks for cheques to be made payable to "The Ken Livingstone Campaign Fund".

The "donate" section of the website states that "every pound is going towards helping Ken's re-election campaign".

Tory MP Greg Hands has made a formal complaint about Mr Livingstone's funding, declaring that he was effectively hiding the sources of his donations. Election watchdogs have since been probing his claims in detail.

An Electoral Commission spokesman told the Standard: "We have received a letter and we are currently reviewing the specific issues it raises. We are in the process of reviewing how donations are being solicited by this website and the implications for reporting."

Peter Wardle, the chief executive of the commission, let slip to MPs on the Commons Justice Committee the issue was being looked at. But his office insists no formal inquiry has yet been launched.

Officials are checking whether the law has been broken. Labour insisted Mr Livingstone's website made clear all donations would go to the Labour Party nationally.