By Estelle Shirbon
LONDON (Reuters) - London Mayor Boris Johnson has denied unfairly favoring the winner of a contract to design a "garden bridge" over the Thames, an awkward controversy as he positions himself to potentially become the next prime minister.
As the most prominent campaigner for Britain to vote to leave the European Union in a June 23 referendum, he is going against Prime Minister David Cameron and could be well placed to replace him depending on the outcome of the vote.
A committee of elected London Assembly members criticized the mayor over the tender process for the 60,000-pound ($87,000) design contract for the new bridge, a pedestrian river crossing which would create a new green space in the middle of the city.
The committee said Johnson met five times with the winning designer before the procurement process began. One meeting was during a taxpayer-funded trip to San Francisco to seek funding for the 175-million pound project.
"The mayor's actions undermined the integrity of the process in terms of the contact he had. No other bidders had that contact with him," Len Duvall, chair of the committee that produced the report, told Reuters.
A spokesman for Johnson said an audit had found the procurement process was "open, fair and transparent".
The contract was won by Thomas Heatherwick, who previously designed an "Olympic Cauldron" for the London 2012 games and a new model of double-decker bus for the capital. A spokeswoman for Heatherwick's studio declined to comment.
The London Assembly committee questioned Johnson about the issue at a heated meeting in December. A transcript shows that he twice dismissed their misgivings as "a load of cobblers".
"The mayor uses colorful language to try and dismiss some very real concerns," said Duvall, an Assembly member from the opposition Labour Party, adding that the tendering process "was not done properly".
Three committee members from Johnson's Conservative Party refused to endorse the report. However, in a minority report, they said the mayor's office should "dramatically improve its recording of details of official mayoral meetings including attendees and headline topics discussed."
Opponents say the Garden Bridge would be an unnecessary extravagance and are critical of its status as private rather than public property.
(Editing by Robin Pomeroy)