They are speaking to the Tory peer's former friend, Michael Stacpoole, who said he was prepared to help police.
Mr Stacpoole, who lives in the red-light area of Pattaya in Thailand, claimed Lord Archer paid him pounds 40,000 to leave the country so he could not give evidence during the 1987 libel case against the Daily Star.
Lord Archer won pounds 500,000 in damages from the newspaper after it claimed he had sex with prostitute Monica Coghlan. Mr Stacpoole claims that Lord Archer reneged on an agreement to pay him half. In a newspaper interview, Mr Stacpoole said last month that Lord Archer misled the trial about the state of his marriage.
He also claimed that the late Terence Baker, who provided an alibi for Lord Archer, was allowed to sell the television rights to his books.
Mr Stacpoole, 61, also said that Lord Archer had a five-year affair with his personal assistant, Andrina Colquhoun.
He said in the interview: "My evidence under cross-examination would have blown his case apart and he knew it."
Lord Archer stepped down from the race to be London mayor after admitting he had his friend, Ted Francis, provide him with a false alibi.
The Star has demanded that Lord Archer pay back damages he won from the newspaper with costs and interest which could total pounds 3m.Reuse content