Claims the Tories offered peerages to senior Brexit Party figures could amount to "political corruption of the highest order", the Labour Party chairman has warned, as Scotland Yard assesses allegations of electoral fraud.
Ian Lavery said the claims that the Conservatives offered Brexit Party leader Nigel Farage and his colleagues seats in the House of Lords in return for standing aside in the General Election are an "absolute outrage".
He said said if the allegations were true it "could be political corruption of the highest order".
He said that merely "assessing" the claims was not good enough and demanded a full police investigation to establish whether any criminal acts had been committed.
"I think it's unbelievable what's happened here. It really is," he said.
"If what Nigel Farage suggests is true, that Brexit Party members have been approached by senior Conservatives asking to step down with the result being peerages, what state of affairs is our politics in? It's an absolute outrage.
"This could be political corruption of the highest order and in addition to that it could be seen as criminal activity. This cannot be accepted.
"There should be undoubtedly an investigation into the situation."
Lord Falconer wrote to the Metropolitan Police Commissioner and Director of Public Prosecutions calling for a probe into what he said were "exceptionally serious allegations".
The Labour former lord chancellor said it should be investigated as a matter of urgency and must be looked at by police in order to maintain public confidence in the integrity of the election.
His letter to Dame Cressida Dick and Max Hill QC refers to Mr Farage’s claim that he and eight other senior figures within the Brexit Party were offered peerages.
The Metropolitan Police said: "The MPS has received two allegations of electoral fraud and malpractice in relation to the 2019 General Election.
"The MPS special enquiry team is responsible for investigating all such criminal allegations. Both allegations are currently being assessed.
"The MPS will not be providing comment about individual cases."
Mr Farage has claimed he had repeatedly been offered a seat in the House of Lords in an attempt to persuade him to "go quietly".
He said when that failed, people working "deep inside Number 10" had tried to bypass him, going directly to senior Brexit Party figures and suggesting eight of them could be made peers if they could persuade him to withdraw more of his candidates.
In his letter, senior peer Lord Falconer wrote: "I wish to raise with you as a matter of urgency a number of recent reports in which senior figures in the Brexit Party have alleged that some of their candidates had been approached by the Conservative Party in an effort to persuade them to withdraw their candidacies from the upcoming General Election."
He added: "I believe these allegations raise serious questions about the integrity of the upcoming General Election, and in particular whether senior individuals at CCHQ or No. 10 have breached two sections of the Representation of the People Act 1983."
He then cites the parts of the Act which refers to "bribery" and "corruptly", inducing or procuring someone to withdraw from being a candidate at an election.
The Prime Minister acknowledged that there may have been “conversations” between senior Tories and people in the Brexit Party, but flatly denied there had been any offers of peerages, saying that was “just not the way we operate”.
He told ITV News Political Editor, Robert Peston, "I have no knowledge of anything."
He added: "Look at what is happening, this Conservative Party is fighting in every seat, we don't do deals with any other party and I think I have been pretty consistent on that."
"I'd be amazed if they did that," Mr Johnson said.
But Lord Falconer said: “These are exceptionally serious allegations which the DPP must, in accordance with his statutory duty, fully investigate as a matter of urgency.
“In addition, in order to maintain public confidence in the integrity of our electoral processes and this election, it is crucial that the Metropolitan Police also examine these accusations.”
The row came amid growing pressure on Mr Farage in the run-up to the close of nominations on Thursday to stand down Brexit Party candidates in all but a few dozen constituencies to avoid splitting the pro-Leave vote.
The Brexit Party leader had already said they would not contest the 317 seats which the Conservatives had won in the 2017 election.
Suspicions that individual Brexit Party candidates were coming under pressure to stand aside were heightened after the prospective candidate for Dudley North announced he would not be running.
Rupert Lowe, a Brexit Party MEP and former chairman of Southampton FC, revealed his decision as nominations were closing – meaning it was too late for the party to put forward an alternative.
Lord Falconer’s letter includes a mention of Ann Widdecombe, the former Tory MP now standing for the Brexit Party in Plymouth Sutton and Devonport.
Ms Widdecombe said she was offered a role in the Brexit negotiations if she was prepared to stand aside.