LONDON Mayor Boris Johnson was told yesterday to come clean over reports he flew to San Francisco at taxpayers’ expense to lobby for funding for a bridge before procurement began.

Garden Bridge, a proposed pedestrian bridge over the River Thames, has been dogged by controversy since the project’s inception.

This week it was reported in the Architects’ Journal that Mr Johnson flew to the US to lobby global computer giant Apple for sponsorship alongside architect Thomas Heatherwick — then vying for the contract to design the bridge — in February 2013.

Mr Heatherwick went on to win the Transport for London contract.

London Assembly Labour group leader Len Duvall said that if the allegations were true it would show “the utter contempt Boris has for the rules which are specifically in place to prevent undue influence.

“What you’ve got is the mayor clearly supporting the Heatherwick bid, indeed actually fundraising for it, before the procurement process had even been announced.

“There can be no doubt that the mayor had a deep conflict of interests and that TfL’s processes appear to have been undermined from the start.”

Mr Johnson’s spokesman said: “The mayor met with Apple in 2013 to discuss a number of investment opportunities in London. Thomas Heatherwick was also in California to meet a separate commitment with Apple.

“Given that he had already expressed interest in creating a Garden Bridge, the mayor invited him to join the meeting and outline his ideas.”

The spokesman denied that the meeting had had any bearing on the procurement process.