Bradford's controversial election system has been hailed a success with 51.25 per cent of the district's 330,000 electorate casting their postal vote.

But there have been more allegations of electoral irregularities with police today admitting they are investigating an alleged theft of ballot papers in Bradford.

Despite problems afflicting the postal voting system across the north of England elections minister and Shipley MP Chris Leslie said he was pleased with Bradford's 51 per cent turnout. It is the largest turnout in more than a decade in the district.

A total of 169,124 people voted by post compared with the 110,000 who voted last year.

Mr Leslie said: "Around 60,000 more people have taken part and been engaged in local democracy - I would call that successful." The only comparable turnout in recent times was at the height of the poll tax debate in 1990, when 52.7 per cent of the electorate voted.

Yorkshire and Humberside was one of four regions chosen for the postal voting experiment by the Government.

The decision to go ahead in all four was made against the advice of the Electoral Commission - and against the wishes of many people in local government.

Across the chosen regions there have been difficulties and in Bradford police have investigated seven allegations of "voting impropriety" which were unsubstantiated. Throughout the ballot there have been allegations of people entering homes and demanding ballots, voting papers going missing and voters being bullied into voting for particular candidates.

A police spokesman said: "We are currently looking into one allegation of theft of three ballot papers from an address in Bradford.

"It is the only ballot-related investigation that is ongoing. It came to us direct and was not passed from the Council."

Five more allegations are now being investigated by the district's returning officer, and could be referred to the police. Earlier this week the district's Liberal democrat leader, Councillor Jeanette Sunderland, said concerns over fraud would always leave the result in doubt.

But Mr Leslie is convinced it will be upheld: "We can always improve things and will continue to review it, but the safeguards are stronger than ever."

However Skipton MP and former Conservative local government minister, David Curry, said the reasons for postal voting were flawed. "To say that this has been a problem about people's willingness to go to the polling stations to vote is both patronising an entirely wrong," he said. "I am glad there has been a high turnout, but I think there are enormous concerns about the integrity of the ballot, and I am absolutely not convinced this is an election which has been as clean as conventional ballots have been."

Keighley Labour MP Ann Cryer added: "If we have pushed the turnout up from 33 per cent to nearly 50 per cent it has been extremely worthwhile.

"I do think that if we were to have an all-out postal ballot again we would have to look at the problems we had this year."

However Mr Leslie dismissed claims of fraud and intimidation saying: "There has always been a history of duress and even violence in Bradford elections. We will see whether any of these local anecdotes are backed up by evidence, and whether any prosecutions take place."