An attempt by Birmingham City Council to check the validity of postal-vote applications is doomed to fail and will simply play into the hands of fraudsters, senior politicians claimed last night.

Fewer than four per cent of the 50,000 people registered to vote by post at the General Election have responded to a letter from the council designed to find out if their requests are genuine.

John Hemming, deputy council leader and prospective Liberal Democrat candidate for Yardley, said ballot-riggers would ignore the letter which asks whether the recipient wants to continue to receive a postal vote and the address to which it should be sent.

All of those who do not ask to be removed from the register will continue to receive a postal vote at the General Election, sparking fears of a repeat of the widespread fraud which marred last year's city-council elections.

An election court in Birmingham heard how an unknown percentage of the 50,000 people, who have to all intents and purposes applied for a permanent postal vote, are the unwitting victims of fraudsters who have made false applications in the names of genuine people from the electoral roll.

Ballot papers, in Aston and Bordesley Green, were diverted to a number of " safehouse" addresses as part of a concerted Labour campaign to rig the vote, the court decided.

Coun Hemming ( South Yardley) said it was also the case that many householders, particularly in Asian communities, who could not speak English, were browbeaten into allowing their postal votes to be sent to different addresses.

Other supposed applicants for postal votes were simply fictitious names, he said.

"If you write to someone who doesn't exist you can't tell anything from the fact that they don't respond.

"To write to ask people only to write back if they are honest isn't very clever," Coun Hemming added.

He is urging council chief executive Lin Homer to take a stronger line by writing again to everyone on the postal vote register asking them positively to opt in if they wish to receive a postal vote.

His suggestion is backed by the People's Justice Party, whose local election candidates were defeated as the result of Labour vote-rigging in Bordesley Green.

PJP spokesman Raghib Ahsan said failure to reply to the letter should not be taken by the council as consent to continue to receive a postal vote.

Mr Ahsan added: "Part of the vote rigging involved the post being intercepted at addresses controlled by landlords or letting agents. Unless such steps are taken we cannot rely on the permanent postalvote register as being safe."

Council elections officer John Owen said he had no legal powers to take people off the postal vote register if they failed to respond to a letter.

He added: "The most we can do is what we have done, which is to invite them to let us know if they want to come off the list of postal voters.

"Timing was also an issue, with the election expected to be called on May 5 at the time we sent out the letters.

Genuine postal voters who did not respond, for whatever reason, would have lost their right to vote by post."

Already, 1,000 people have said they no longer want a postal vote, 300 asked for their ballot forms to be sent to different addresses and 200 wanted more information.