Police have started a drugs investigation following allegations about the private life of Leicester MP Keith Vaz.
Mr Vaz, 59, a married father of two, quit as chairman of the influential House of Commons Home Affairs committee in September after the allegations in the Sunday Mirror.
Scotland Yard said police had received a letter on September 7 asking them to look into matter.
The Metropolitan Police began an assessment process to see "what criminal offences - if any - may have been committed," according to Scotland Yard.
A spokesman said: "Following that assessment, which included obtaining early investigative advice from the Crown Prosecution Service, the MPS is now investigating offences under the Misuse of Drugs Act 1971.
"The investigation started on Thursday, 10 November."
Mr Vaz, the Labour MP for Leicester East, 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.