Some experts believe the report into the simultaneous local and European polls should also say whether certain areas, such as Asian communities which saw the most fraud claims, are unsuitable for all-postal voting.

Police investigations into alleged electoral discrepancies.have been launched in Greater Manchester, Cheshire, Lancashire, West Yorkshire and Derbyshire. Supporters of all parties were involved in the misuse of postal ballots, according to High Court documents calling for the election results to be declared invalid. Two petitions request a judge to overturn elections to Birmingham City Council, Britain’s largest, where postal vote applications rose from 24,000 to 70,000.

Hugh McCallion, Birmingham’s deputy Labour leader, said that the petitions from the Liberal Democrats and the People’s Justice Party involved “wild allegations” and a “scattergun approach”.

One petition claims: “Attempts were made by Labour supporters in Bordesley Green to bribe a postman and he was threatened with having his throat cut. The Royal Mail also changed the colour of their vans from red to white to protect the postmen. Post boxes containing a number of ballots were set alight to invalidate the votes.

“Threats of deportation were made by Labour supporters to first generation migrants if they did not sign postal vote papers to vote Labour. Postal voters were pressurised by Labour Party candidates and agents into casting their vote for the Labour slate whilst the Labour Party agents stood over the voter watching them cast their vote.

“Children were paid to collect postal votes that were sticking out of people’s doors.

“Postal ballots which had been opened, the vote changed and then resealed were accepted as valid votes notwithstanding the evidence that duress (or fraud) may have been used to change the votes (Tippex was used as well as crossing out the vote).”

It is also claimed that a candidate was seen coming into a school “with something under his jumper . . . which turned out to be postal ballots”.

The petition claims that the police were called when candidates were seen taking bags of postal votes to a deserted road. Asian candidates were “from different ethnic groups and did not trust each other. They were expected to show the ballot papers to each other to ensure all three Labour candidates had been voted for”.

Mohammed Kazi, a candidate, later said that they they had been “sorting out” the ballots. “No one has explained what ‘sorting out’ means,” the petition states. Mr Kazi was cleared by police of any wrongdoing.