Indian PM Manmohan Singh denies bribing MPs for votes
Indian PM Manmohan Singh has said no member of his Congress party or government bribed MPs to survive a crucial vote of confidence in 2008.
A diplomatic cable released by Wikileaks says a party aide showed a US embassy official "chests of cash" to pay off MPs ahead of the vote.
Mr Singh said there were doubts about the veracity of such cables.
The leak heaps further pressure on the embattled Mr Singh after a string of corruption scandals.
The vote took place after the government's left-wing allies withdrew their support over a controversial nuclear deal with the US.
But the Congress party narrowly survived the vote despite substantial opposition.
The leaked cable, reported in The Hindu newspaper, has caused uproar in the Indian parliament with the main opposition parties saying that Congress had "brought shame to the nation" and calling on the prime minister to resign.
Mr Singh told parliament that "no one in the Congress party or the government indulged in any unlawful act during the [confidence] vote".
He said a parliamentary committee had investigated the allegations of vote buying in 2008 and had "concluded that it had insufficient evidence to draw any conclusion".
Mr Singh said people had voted the Congress party into power in the general election in 2009 despite the opposition parties "repeating their allegations of bribery in the confidence vote".
The prime minister criticised the contents of the cable, and doubted its veracity.
"It is unfortunate that speculative, unverified and unverifiable communication can be given dignity by the opposition to revive old charges that have been soundly rejected," Mr Singh said.
Earlier Mr Singh told a conclave organised by India Today magazine that he had "no knowledge of any such purchases of votes" ahead of the vote.
"I have not authorised anyone to purchase any votes. I am not aware of any acts of purchasing any votes. I am not at all involved," Mr Singh said.
The cable by US official Steven White said that the embassy employee had met Nachiketa Kapur, an aide of senior Congress leader Satish Sharma.
It says that Mr Kapur told the embassy employee that "money was not an issue at all, but the crucial thing was to ensure that those who took the money would vote for the government".
The embassy employee said he was shown "two chests containing cash and said that around $25m (£15.5m) was lying around the house for use as pay-offs".
Nachiketa Kapur rejected the report, saying: "I vehemently deny these malicious allegations. There was no cash to point out to."
Satish Sharma told a news channel that he did not even have an aide called Nachiketa Kapur.
Mr Sharma is described as a "close associate of former prime minister Rajiv Gandhi [and] considered to be a very close family friend of [Congress party chief] Sonia Gandhi".
The cable said that Mr Kapur also claimed that MPs belonging to regional party Rashtriya Lok Dal (RLD) had been paid 100 million rupees ($2.5m; £1.5m) each to ensure they voted the "right way".
RLD leader Ajit Singh has denied the charge and said that he was "opposed to the nuclear deal" and his party MPs "voted against the government".
If the government had lost the vote, India could have faced early elections. A defeat would have also put the nuclear deal in doubt.