India PM Manmohan Singh: 'Not aware of vote buying'
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 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.
He said there are doubts about the "veracity of diplomatic despatches".
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