An SNP MP has written to the Metropolitan Police calling for an investigation into the government amid a debate on parliamentary standards for MPs.
In his letter, Pete Wishart accused the government of "cash for honours" - a practice of offering peerages for the House of Lords in return for money.
"These widespread allegations and suspicion of criminal activity need to be urgently addressed," writes the MP for Perth and North Perthshire
"I, therefore, believe it is now essential that a formal criminal investigation is now initiated by the Metropolitan Police."
He cites the Tory party elevating nine of the party's former treasurers to the Lords since 2010 and claims those appointed since 2014 have donated "at least £3 million" as grounds for an investigation.
Wishart also claims 22 of the Conservative party's biggest financial contributors have been made members of the Lords since 2010.
"Given that these allegations concern House of Lords appointments specifically made by Prime Ministers, I believe the investigation should naturally focus on the current Prime Minister, former Conservative Prime Ministers since 2010, as well as the Conservative party's processes and policies for fundraising."
Speaking in a debate about parliamentary standards in the House of Commons on Monday night, Wishart said the House of Lords "is so corrupt it’s a receptacle for donors" and called on Labour to "grow up" and to "get rid of that appalling circus".
He was handed a 30-day suspension, but the government moved to prevent the suspension by proposing changes to rules - included reforming the watchdog to have Tory majority committee.
The government performed a U-turn after opposition parties refused to cooperate, and Paterson has since resigned.
Boris Johnson, who has been criticised for failing to attend the debate on parliamentary standards, refused to apologise for the scandal when questioned over the Conservative's management of the issue.
Labour leader Keir Starmer accused Johnson of cowardice for appearing to dodge the debate.
He said: "When the Prime Minister gives the green light to corruption, he corrodes that trust. When he says that the rules to stop vested interests don’t apply to his friends, he corrodes that trust.
"And when he deliberately undermines those charged with stopping corruption, he corrodes that trust. And that is exactly what the Prime Minister did last week.
"And now today, he does not even have the decency either to come here either to defend what he did or to apologise for his actions."
Watch: Minister says it's important to have 'rich mix' in House of Lords amid 'cash for honours' claims