The scale of alleged ballot rigging at last year's Birmingham City Council elections became clear yesterday when a court heard how batches of postal votes, from entire households in Bordesley Green, were tampered with and changed to support Labour.

Correction fluid was used to blank out crosses on ballot papers for the People's Justice Party, the Conservative Party and the Liberal Democrats.

Fresh crosses were added in favour of the three Labour candidates, an election court was told.

The changed votes were counted by election staff and allowed to stand by the returning officer, it is claimed.

The court is considering claims that Labour engineered widespread fraud by fiddling up to 3,000 postal votes, enabling the party's three candidates to beat the PJP.

Graham Brodie, representing PJP supporters who are petitioning the court to have the election result overturned, said that in some instances ballot papers were changed after having passed through the postal system.

There were several examples of a postman handing over bundles of un-used ballot papers to Labour candidate Shah Jahan in the street.

Gangs of children and Labour supporters toured Bordesley Green taking newly-delivered ballot forms from letter boxes and asking householders to hand over completed forms, Mr Brodie claimed.

It was suggested, incorrectly, that electors would be liable to a £5,000 fine if they did not part with the forms.

It is alleged the forms were then taken to safe houses where they were either filled in or, if already completed, changed to favour Labour. One person out of the country in Pakistan was said to have voted along with a person who was in prison at the time of the election. One person, a Mr Watson, apparently filled in three different ballot papers voting each time for the Labour candidates.

More than 90 people gave evidence to the court that they did not apply for a postal vote, but were recorded as voting by post for the Labour candidates.

The court heard further evidence about the status of three ballot boxes at the Bordesley Green count. The boxes contained 1,700 postal ballot forms all marked in favour of Labour in identical handwriting with the same blue pen, it is claimed.

Mr Brodie told the court that the returning officer ought not to have allowed the votes to stand without investigating where the boxes had come from and the validity of the ballot papers.

Deputy High Court judge Richard Mawrey QC said the case for the petitioners was that "alarm bells" should have rung when the contents of the boxes were revealed. Council election officials insist they were correct to allow votes from the boxes to stand. The three Bordesley Green councillors - Shafaq Ahmed, Shah Jahan and Ayaz Khan - deny any wrongdoing.

The hearing continues.