Boris Johnson has claimed that Kate Hoey, the Labour MP for Vauxhall, will join him working in City Hall if be becomes Mayor.

There was no immediate confirmation of the announcement from the former sports minister, who may face disciplinary action if true, including the possibility of being thrown out of the Labour Party.

Ms Hoey was claimed by Mr Johnson to have agreed to serve as a non-executive Director advising Mr Johnson on sport and the Olympics.

According to a release from the Mr Johnson campaign, Ms Hoey would work in an unpaid capacity and intends to remain MP for Vauxhall.

Ms Hoey or her office could not be contacted, but if the annoucement is confirmed Ms Hoey could face losing the Labour whip.

Ms Hoey has long been a critic of Ken Livingstone, and was part of an all-party group calling on the police to investigate grants distributed by the LDA. Last week Ms Hoey pulled out of an event with Mr Johnson at a ballet school in her constituency at the last minute.

Mr Johnson said: “I am delighted to announce that Kate Hoey will join me in my administration if I win on May 1. She and I agree that there is much more that can be done to promote sport and to develop sporting facilities across London.

“I have already pledged to ring-fence London Development Agency money for sport, and if I am lucky enough to win she will be working on an agenda that includes protecting playing fields, boosting sports clubs and making sure that London’s kids all benefit from the Olympics.

"Kate has a huge and well-known commitment to sport and to London, and I am determined to bring talent from across politics and the community to a new administration.”

Last week, when Ms Hoey nearly attended a campaign event with Boris Johnson, she told Times Online: "What about Gordon Brown appointing non Labour Party members to the government. Are we not supposed to speak to people from other parties?" Asked if she was still supporting Mr Livingstone, she said: "I'm a Labour MP. What more do you want."

Ms Hoey has previously predicted Mr Johnson would do "quite well" in the Mayoral contest, and supported the idea of him standing. While she was "in theory'' backing Mr Livingstone, the Vauxhall MP said she was concerned that the mayor's office had made him "a kind of elected dictator''.

Ms Hoey said last July: "I think if (Mr Johnson) is the candidate I think he will bring a lot of interest to the campaign and he will certainly not stick to party scripts, which is probably what Londoners want.

"They don't want to see party scripts, that's why they elected Ken originally, but...''

Ms Hoey said that while she was "in theory'' backing Mr Livingstone, "in practice I actually do think that there is a debate to be had about how London is being governed and about the role of the Mayor and about just how the Mayor's functions are working, because I think for a lot of people there's a feeling that the Mayor perhaps is a kind of elected dictator'.'

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