A senior MP tipped to run as the Tory candidate for Mayor of London would be breaching the ministerial code if he took on Sadiq Khan, it has been claimed.
Minister for London Paul Scully is expected to officially announce he is running for the Conservative nomination this week.
But the Liberal Democrats have said the Sutton and Cheam MP could be breaking Government rules if he throws his hat into the ring.
MP Sarah Olney has written to ethics advisor Sir Laurie Magnus asking that he launches an investigation if Mr Scully declares his intention to stand in the City Hall election next May.
She said she is "concerned" that there would be a conflict of interest if Mr Scully continued to be a minister while campaigning to be MAyor of London and it would give the impression that "Government resources at his disposal as Minister for London would be being used for the purposes of his potential candidacy".
"I therefore would urge you to open an investigation under article 1.3f of the Code, should Scully announce his intention to seek the nomination," Ms Olney wrote in her letter.
But Mr Scully hit back, saying he would “happily” relinquish his ministerial role and pause “all Minister of London activities” if he declared he wanted to run.
He told the Standard: “Rather than drowning in an attempt to remain politically relevant like the Lib Dems I’m concentrating on improving the lives of Londoners, especially on crime, transport and housing.”
Several Tory candidates have declared they want to take on Labour's Sadiq Khan, who will fight for a historic third term next year.
Three Tories on the London Assembly - Andrew Boff, Nick Rogers and Susan Hall - have all said they will stand.
Samuel Kasumu, a former Downing Street aide to Boris Johnson, tech entrepreneur Daniel Korski, and ex councillor Duwayne Brooks have entered the race, while former Education Secretary Kit Malthouse has also refused to rule out a bid.
