An investigation was today under way to discover why 229 more votes were recorded than there were ballot papers issued in the election of a Wolverhampton MP.

Conservative Paul Uppal, who became the MP for Wolverhampton South West in May, ousting Labour’s Rob Marris after nine years in the post, has raised concerns about possible postal voting fraud in the Election.

It can also today be revealed that the Labour, Tory and Lib Dem candidates and their agents knew of the discrepancy as soon as votes were counted. But they agreed to accept the result as it was not enough to affect Mr Uppal’s majority of 691.

In the House of Commons during questions to Deputy Prime Minister Nick Clegg before the summer recess Mr Uppal asked: “What measures is the Deputy Prime Minister taking to tackle postal voting fraud, which particularly affected me during the last general election?”

Today Wolverhampton City Council promised it was looking into the matter but said there was no evidence of postal voting fraud. Elections watchdog the Electoral Commission has asked for an explanation.

The total number of votes cast between five candidates along with spoiled papers in Wolverhampton South West came to 40,323, which is 229 more than the 40,094 ballot papers official records say were issued.

Meanwhile it was revealed that an allegation was made to police of postal vote fraud during the election campaign in the constituency but no-one was arrested.

Today Mr Uppal declined to elaborate on the details of the allegation to protect the identities of constituents who had raised concerns, but he said: “We are not saying there is a link but we believe more needs to be done to reassure the people of Wolverhampton South West that no irregularities occurred during the vote.”

West Midlands Police today confirmed it had received an allegation concerning postal voter fraud in Wolverhampton South West but did not have sufficient evidence to pursue it.

Chief executive of Wolverhampton City Council Simon Warren said today he was aware of the problem with the count before he announced the result.

“This council takes the integrity of the electoral process extremely seriously,” he said. The discrepancy in Wolverhampton South West between the amount of ballot papers issued and the amount counted was picked up by our electoral staff on the night of the count.” Both Rob Marris and Liberal Democrat candidate Robin Lawrence declined to comment.

West Midlands Police today confirmed the force had received an allegation concerning postal voter fraud. Acting Det Ch Insp Andy Bannister said: “There was no evidence to corroborate the allegation. The person who made it was asked to provide other evidence which has not been forthcoming.”