Hussain Akhtar, a Blackburn councillor considered to be the foreign secretary’s right-hand man in the town’s Muslim community, would not discuss the matter with The Sunday Times but said the voters were ‘gone’.

The property was boarded up with ‘Vote Labour’ placards during the election campaign. One of the listed tenants was first registered to vote at Akhtar’s property about two years after she says that she left.

The case emerged as concerns grow about the accuracy of the electoral roll and the potential vulnerability of the election system to abuse. The Electoral Commission has called for new laws to improve their administration.

There is no evidence that Akhtar has been involved in wrongdoing, but he is under pressure to explain how the 10 voters ‘ and himself ‘ are registered in a property which appears to be empty.

Tony Melia, the Liberal Democrat candidate for Blackburn who came third in Thursday’s poll, said: ‘I have made a complaint about this matter to Jack Straw.

‘We need to know why these people are registered at this address, who registered them and, most importantly, whether they voted. I am particularly concerned at voters who are registered and moved out some years ago.’

Labour had feared that Straw would lose many votes over the Iraq war. Akhtar was one of the campaigners used to mobilise the Muslim vote.

One of the tenants on the electoral roll at Akhtar’s property in Whalley Range, Blackburn, is Afrin Hussain. Electronic records of the electoral roll indicate that she was first registered there in 2002, although the spelling of her first name was then Afrian.

She said yesterday that she had moved out five years ago and was now listed on the electoral roll at a separate address with her husband. She had voted in the election.

‘We just don’t know how we got registered at Whalley Range. I will go to the council next week and tell them what has happened,’ she said.

Most of the voters at the address are thought to be part of Akhtar’s extended family. ‘Some people have been moved to different addresses and everybody knows it. The people have moved from here, they are gone,’ he said.

In other constituencies some candidates said they believed the lack of checks on the electoral roll and voting process may have resulted in fraud. In Birmingham Ladywood Ayoub Khan, the Liberal Democrat candidate, has called for an inquiry into allegations of ‘personation’ ‘ voting under someone else’s name ‘ and hopes to challenge the result.