A Labour backbencher has accused the government of corrupting the parliamentary system by pushing through a private bill giving greater voting rights to the City of London.

Speaking in the Commons on Monday, Hayes and Harlington MP John McDonnell called for an inquiry, claiming he had proof that a Commons motion allowing the house to sit throughout the night had been tabled by the prime minister following pressure from the City Corporation.

The City of London (Ward Elections) Bill is designed to give an increased number of votes to businesses in the area, due to the low residential population.

A number of Labour MPs argue that this is undemocratic, and have been fighting the bill for three years.

After the sitting, it was given a third reading with a majority of 248 votes.

"Can I ask you to confirm, or investigate that this motion has been placed on the agenda at the direct request of the City Corporation because I have evidence to prove that it has," he asked deputy speaker Sir Alan Haselhurst.

"On repeated occassions we have been informed that this is a private bill and not a government bill and yet the prime minister's name is now associated with this bill.

"Votes are being sold to business friends who have donated to both parties. It is a corruption of the worst kind to debase parliament in this way."

McDonnell claimed that he had been offered inducements to withdraw his opposition to the bill. He called for an inquiry to examine the relationship between Downing Street and the City Corporation before leaving the debate in protest.

"This is meant to be private business, not government business," he said.

"But the government and the prime minister has personally intervened to undermine any prospect of a backbencher exerting influence on private business. This process is tainted and corrupted."

Local government minister Nick Raynsford rejected the claims.

"He [McDonnell] made a series of wholly and unfounded allegations, imputing motives to the prime minister and the government for which there is no basis whatsoever and which I unequivocally rebut," he said.

"The government's concern is this is quite simply to assist the passage of a private bill, which is a modest measure of reform which most sensible minded people recognise as a step in the right direction."Haselhurst called on the MP to hand any evidence to the Parliamentary Commissioner for Standards, despite a call by Labour MP Robert Wareing for the debate to be suspended until an investigation had been made.

Thurrock MP Andrew MacKinlay said it was "a very bad day for parliament."

"It's a disgraceful day that the government machine and the minister can railroad through legislation which in an ordinary free debating environment would not get on the statute book," he said.