The Met Police referred the investigation onto the Essex force having shelved its own investigation into the Solihull MP in March.

It is not clear why the case was referred onwards.

Mr Knight has been an MP since 2015. The Conservatives stripped him of the party whip when allegations first emerged, and he sits as an independent.

The Conservative Party refused to restore the whip to Mr Knight after the Met dropped the case, with the party saying at the time that it had received "further complaints".

Mr Knight has denied what he described as a "false and malicious accusation".

On Tuesday, a statement from Essex Police said: "We have agreed to take on an investigation which has been referred to us from the Met Police Service.

"We are investigating an allegation of serious sexual assault.

"Detectives who specialise in cases of this kind will gather evidence and conduct a thorough investigation."

Det Ch Supt Andy Waldie will oversee the work carried out by a senior investigating officer with "extensive experience".

"In the interests of justice and of all concerned, we have asked media outlets and others not to enter into any speculative comment or reporting on this matter," Essex Police added.

"We would also remind everyone that victims of sexual offences are entitled to life-long anonymity, regardless of how a case proceeds.

"The Essex Police investigation remains at an early stage."

The Met Police in a statement said: "We had been liaising with Essex Police about an investigation which they are now leading on. This was agreed by both the Met Police Service and Essex Police.

"Whilst we will not comment on this case specifically, as part of any investigation where safeguarding is a factor, liaison with relevant partners and authorities takes place."

Mr Knight has been approached for comment.