The man in his 50s has since been bailed, the Metropolitan Police said, after being detained on Saturday over allegations of four separate incidents between July 2019 and January 2020.

The Sunday Times reported that the allegations related to a former parliamentary staffer, who said she was assaulted by the MP, forced to have sex and was left so traumatised she had to go to hospital. 

The woman, in her 20s, also accused him of coercive control.

The paper also reported that Tory chief whip Mark Spencer and Commons leader Jacob Rees-Mogg had previously been made aware of the allegations.

Sources said Mr Spencer did not realise the "magnitude" at the time and did not believe a sexual assaut had been disclosed to him.

But a spokesman for the chief whip said he took all allegations seriously, and urged anyone who had contacted him to report such incidents to the authorities.

A Conservative Party spokesperson said: "We take all allegations of this nature extremely seriously. As this matter is now in the hands of the police it would be inappropriate to comment further."

The Sunday Times said the alleged victim had reported the case to the Independent Complaints and Grievance Scheme, set up in 2017 to allow parliamentary employees to report bullying and harassment and sexual misconduct. 

A Met Police spokesperson said: "On Friday, 31 July, the Metropolitan Police Service received allegations relating to four separate incidents involving allegations of sexual offences and assault.

"These offences are alleged to have occurred at addresses in Westminster, Lambeth and Hackney between July 2019 and January 2020.

"A man in his 50s was arrested on Saturday, 1 August on suspicion of rape. He has been released on bail to return on a date in mid-August."

It comes just days after ex-Tory MP Charlie Elphicke was found guilty of three counts of sexual assault.

Southwark Crown Court heard that Mr Elphicke allegedly attempted to kiss and grope a parliamentary staffer after a drink in Westminster in 2016, and and that he had later slid his hand up her thigh towards her groin.

He will be sentenced next month, with the judge warning "all options", including custody, remained on the table.