Furious Labour officials have demanded the head of a Conservative MP who launched an astonishing attack on his general election opponent in the House of Commons.
Shrewsbury MP Dan Kawczynski (Con) said in the House that he had been told his rival, Labour councillor Jon Tandy, cheated in local council elections.
The MP then demanded assurances Labour candidates won't be allowed to "manipulate postal votes" when the General Election comes.
Labour condemned the accusations as "absolutely unfounded" and demanded that Mr Kawczynski resign if police find no evidence of wrongdoing.
The MP spoke during a debate on Britain's electoral system. His comments, made in a Commons debate, were covered by Parliamentary privilege, which means he cannot be sued for libel.
Shrewsbury is a marginal seat which the Conservatives won in 2005 with a majority of 1,808 over Labour.
Mr Kawczynski made claims about "certain Labour councillors" and "the Labour parliamentary candidate selected to stand against me".
This is Jon Tandy, a Royal Mail worker, who is a member of Shrewsbury & Atcham Borough Council and Shropshire County Council.
He said: "There have been allegations in Shrewsbury against certain Labour councillors who work in our local post office; indeed, I have received these allegations myself repeatedly.
"What can I do if they are anonymous? However, the situation is imprinted on one’s mind.
"One ultimately thinks, 'Yes, they work in the post office. They could, as Labour party activists, play some role in manipulating postal votes.' What is the Minister going to do to ensure that Members of Parliament such as I can have confidence in the process?
"Now, I find out that the Labour parliamentary candidate selected to stand against me also works in the sorting office at Shrewsbury post office."
He added later: "The Labour party has selected somebody who works at Shrewsbury sorting office to stand against me.
"I am starting to get allegations that he, when he stood to be a councillor, was also implicated in various fraudulent practices. I am not saying that; my constituents are."
In an angry statement yesterday, Ian Reilly, Regional Director of the Midlands Division of the Labour Party, said: "We are shocked.
"I am sure that people in Shrewsbury do not want an MP who makes unfounded and cowardly allegations – let alone one who is only prepared to make them in the House of Commons where he can hide behind parliamentary privilege."
"As far as we are concerned this is nothing more than a political smear by the MP for Shrewsbury. These allegations are absolutely unfounded. If Daniel Kawczynski has any evidence then he should refer this matter to the police.
"And when the police find that the allegations are unfounded then we will be asking Daniel Kawczynski to consider his position as a Member of Parliament. "
Speaking outside the Commons last night, Mr Kawczynski said he had now fowarded his concerns to the police.
Mr Kawczynski added: "These are issues of concern to me and my constituents and it is right that I should raise them in the Commons."