Police are to "assess and identify what criminal offences - if any - may have been committed" in the wake of Sunday newspaper revelations about Labour MP Keith Vaz.
Mr Vaz, 59, a married father of two, quit as chairman of the influential House of Commons Home Affairs committee on Tuesday after becoming embroiled in the rent boy scandal.
The Leicester East MP had a conversation regarding cocaine with one of the male escorts in which the MP said he did not want to use the drug, but indicated that he would pay for it for the other man at a later date, according to the Sunday Mirror.
In the wake of the revelations, Tory MP Andrew Bridgen, who has been highly critical of Mr Vaz, indicated that he would be writing to Scotland Yard calling for Mr Vaz to be investigated for misconduct in a public office and conspiracy to supply controlled substances.
Scotland Yard released a statement on Friday saying: "Following allegations in the Sunday Mirror on Sunday 4 September concerning a Member of Parliament, the Metropolitan Police Service can confirm a letter was received on Wednesday, 7 September requesting police consider the matter.
"The letter has been forwarded to the Met's Special Inquiry Team, part of Specialist Crime and Operations, to assess and identify what criminal offences - if any - may have been committed.
"At this stage a police investigation has not been launched."
Announcing his resignation on Tuesday, Mr Vaz said "those who hold others to account must themselves be accountable".
He had come under increasing pressure following claims that he paid two male escorts he met at a flat he owns near his family home in north London last month.
He said: "It is in the best interest of the Home Affairs Select Committee that its important work can be conducted without any distractions whatsoever. I am genuinely sorry that recent events make it impossible for this to happen if I remain chair.
"I have always been passionate about select committees, having served as either chair or member for half of my time in Parliament. The integrity of the select committee system matters to me. Those who hold others to account, must themselves be accountable."
He insisted he was "immeasurably proud" of the work the committee has carried out over the last nine years, adding that he is "privileged to have been the longest serving chair of this committee".
The announcement came after the Mirror newspaper published new transcripts of a recording of the MP talking with the two escorts, which it said scotched suggestions that he was the victim of a "press sting".
According to the paper, the tape showed Mr Vaz telling one of the men to treat the other as his "bitch" and discussing having sex.
Mr Vaz said the decision to resign and stand aside immediately from the committee's business was "my decision, and mine alone" and "my first consideration has been the effect of recent events on my family".
He had faced claims that the committee's investigations into issues like prostitution or drugs could be undermined if he remained as chairman.