Prime Minister Rishi Sunak has described allegations that a Conservative MP committed multiple rapes as “very serious”.
He urged anyone with evidence of criminal acts to go to the police.
It comes after reports that former Tory Party chairman Sir Jake Berry wrote to police to make them aware of the claims after leaving the post last year.
Labour and the Lib Dems have called for an investigation by the party into how it handled the accusations.
Sir Jake told police a failure of some individuals to act allowed the alleged perpetrator to “continue to offend”, the Mail on Sunday reported.
Mr Sunak said the Conservative Party had “robust independent complaint procedures in place”.
During a visit to Bacton Gas Terminal in Norfolk, the prime minister was asked whether the rape allegations had been covered up and whether he was investigating the issue.
He told broadcasters: “These are very serious, anonymous allegations.
“It may be that they allude to something that is already the subject of a live police investigation, so I hope you understand it wouldn’t be right for me to comment on that further specifically.
“More broadly the Conservative Party has robust independent complaint procedures in place, but I would say to anybody who has information or evidence about any criminal acts to of course talk to the police, that’s the right course of action.”
On Sunday, Deputy Prime Minister Oliver Dowden, who was previously party chairman between September 2021 and June 2022, denied the party had covered up allegations.
However, he said he could not comment on the specific case as he did not know the identity of the unnamed MP.
Sir Jake, the MP for Rossendale and Darwen, was chairman of the Tory Party during Liz Truss’s 49-day premiership last year.
According to the Mail on Sunday, he became aware of a series of allegations against an MP – referred to as X – when he was appointed to the role in September 2022.
The newspaper said that after leaving the post the following month, he wrote to police with former Chief Whip Wendy Morton to express his concerns about how the party had handled the claims.
According to extracts of the letter published by the newspaper, he said the matter had been going on for more than two years, adding: “The failure of others to act has enabled X to continue to offend.”
A published extract reads: “There may have been five victims of X – who have been subject to a range of offences including multiple rapes.”
It also claims one unnamed individual was receiving ongoing support at the expense of the Conservative Party.
Conservative MP Caroline Nokes, who chairs the Commons Women and Equalities Committee, said the case was “horrific”.
She told BBC Radio 4’s Woman’s Hour political parties needed transparent processes in place for when individuals made complaints, with alleged victims supported to go to the police.
“My sense is one of horror and despair that still we haven’t got in place a mechanism that will support victims, that will make sure that individuals who are accused of horrific acts are not still free to wonder around Parliament, free to meet with their constituents in constituency surgeries,” she said.
Labour Party chairwoman Anneliese Dodds said the allegations were “deeply concerning” and needed to be “thoroughly investigated by the Conservative Party”.
Also calling for an investigation, Liberal Democrat chief whip Wendy Chamberlain said the reports were “deeply disturbing”.