The deputy leader of Birmingham City Council has started a legal process that could force Tony Blair to postpone the General Election until adequate safeguards are in place to prevent postal vote fraud.

John Hemming wants the High Court to allow a judicial review into the Prime Minister's decision to go to the country on May 5.

Coun Hemming, who is the prospective Liberal Democrat parliamentary candidate for Birmingham Yardley, said he was taking the unprecedented step of attempting to block the election because of the "very real likelihood" that scores of inner city constituencies across the UK would be riddled by ballot rigging.

His stance follows the report on Monday by Richard Mawrey QC, the election commissioner, who found widespread postal vote fraud at last year's Birmingham City Council elections. Mr Mawrey sacked six Labour councillors in Aston and Bordesley Green and hit out at what he called "massive, systematic and organised" corruption by the local Labour Party.

Mr Mawrey warned the Government there were no effective safeguards in place to prevent similar levels of fraud at the General Election, where 50,000 people in Birmingham have already registered to vote by post. The system of registering postal votes was "hopelessly insecure", what went on in Birmingham would disgrace a banana republic and the Government was in denial over the entire subject, he added.

Coun Hemming helped raise an election petition in Aston, which led to the election court being summoned, and is a seasoned campaigner in the art of applying for judicial reviews.

His bid to stop the General Election has the backing of the Liberal Democrat Party nationally.

A self-made millionaire special-ising in IT, Coun Hemming is prepared to bankroll the judicial review process which will cost at least #10,000 to get to the stage of a full High Court hearing.

Coun Hemming said: "More and more people recognise how serious the problem is. The General Election will be wide open to fraud if steps are not taken immediately to tighten postal vote procedures.

"We need to get democracy back into the system and the outcome of the election court in Birmingham has shown that it is possible to use the law to get things changed."

He accepts that most people will dismiss his chances, but added: "Someone has to take a stand. What took place in Aston and Bordesley Green appeared surreal and you wouldn't have thought it could have happened. But it did happen. This is not just happening in Birmingham. It is taking place all over the country and it has got to stop."

The basis of Coun Hemming's case is that the absence of a secure system for postal voting contravenes the Human Rights Act because the secret ballot is compromised.

In an outline of his case, faxed to The Treasury yesterday, he is demanding key changes to the law before an election can be held: n Postal votes must be counted separately to non-postal votes; n Political parties must be permitted to check application forms for postal votes; n The period for election petitions to be raised should be extended to two months from 21 days.

A High Court judge will decide whether Coun Hemming's request passes the first hurdle, which is to give permission to proceed to a judicial review.

Coun Hemming said: "It's very difficult to judge what will happen because there are a lot of constitutional issues involved. I would have thought it has a reasonable chance of getting past the permission stage because of the importance of the issue and the fact the commissioner made the comments he did."

However, a Labour spokesman in London, said: "To argue that holding an election is a contravention of the Human Rights Act is patent rubbish."