Boris Johnson has defended the decision not to suspend a senior Tory MP who was arrested on suspicion of rape.

The Prime Minister insisted on Thursday that the allegation is being taken “extremely seriously” after the Conservatives defied calls to remove the whip from the former minister.

Mr Johnson, in his first comments about the arrest, said a decision will be made when the police investigation is concluded.

“I think it’s very, very important that we take all these cases extremely seriously and we will continue to do so,” he told reporters during a visit to Warrington.

“I think we’ve got to wait for the police to decide whether they want to make charges and take a decision on that basis.”

On Friday, Scotland Yard received allegations of sexual offences and assault relating to four incidents at addresses in London, including in Westminster.

The unnamed MP was arrested the following day on suspicion of raping the woman and was taken into custody before being bailed until mid-August.

Labour’s shadow safeguarding minister Jess Phillips was among those who criticised the Tories for not suspending the whip from the MP.

She told Times Radio it sent a “terrible message” that powerful figures can secure “protection” with their Westminster status.

“While pending a police investigation for a sexual crime, I think it is only right that the whip is withdrawn,” she said.

The investigation was launched days after former Tory MP Charlie Elphicke was convicted at Southwark Crown Court in a separate case of sexually assaulting two women.

He had the whip removed in November 2017 when the allegations first surfaced, but it was controversially restored before a confidence vote in then prime minister Theresa May’s leadership the following year.

But the party suspended him again on the day Elphicke was formally charged in July 2019.