The judge who warned of a "Birmingham-wide" campaign of postal voting fraud by the Labour Party was wrong, the Government claimed yesterday.

Nick Raynsford, the Minister responsible for local government, told the House of Commons he had personally read the evidence and did not agree with the judge's conclusions.

And he rejected calls for fundamental reform of the postal voting system.

Mr Raynsford was making a statement in response to a damning High Court judgment which found six Labour councillors in Aston and Bordesley Green guilty of trying to rig the 2004 city council elections.

Richard Mawrey QC, the Election Commissioner, said on Monday: "I was forced to conclude that Bordesley Green and Aston were not isolated incidents but were part of a Birmingham-wide campaign by the Labour Party to try, by the use of bogus postal votes, to counter the adverse effect of the Iraq war on its electoral fortunes."

In the first finding of fraud and corruption by an elections court for more than 100 years, Mr Mawrey said he had heard "evidence of electoral fraud that would disgrace a banana republic".

But yesterday Mr Raynsford said he did not believe the findings.

He told MPs: "I do not accept the judge's claim that there was a Birmingham-wide campaign by the Labour Party.

"The evidence, and I have read the evidence carefully, relates to two wards in Birmingham.

"But it is a different matter to conclude, without supporting evidence, that there was a city-wide conspiracy as implied."

The judge had also accused the Government of being in "a state not simply of complacency but of denial" about the scale of the problem.

But Mr Raynsford also rejected this claim.

He was criticised by Sir Patrick Cormack (Con Staffordshire South), who said he had broken Commons rules by attacking the judiciary.

But Mr Raynsford repeated his comments that the judge was wrong to make the claims that the fraud had been city-wide and that Labour had been complacent, "neither of which were supported by the evidence".

Mr Raynsford said: "Contrary to suggestions that have been made, the Government is not complacent."

He said there would also be "new initiatives with the police to ensure offenders are bought to justice".