New Delhi - India's opposition parties on Wednesday alleged Prime Minister Manmohan Singh's government had won a crucial trust vote by unfair means.

Singh's United Progressive Alliance (UPA) government won a confidence motion on Tuesday by 275 votes to 256, with 10 lawmakers abstaining.

In a drama-packed day at parliament, at least 10 lawmakers of the opposition parties voted for the government in the motion brought on after the left parties withdrew their support to the government over a controversial nuclear deal with the United States.

Ten lawmakers of the Samajwadi Party, a regional party from northern Uttar Pradesh state which was backing the UPA ,also went against their party whip.

There were also several abstentions, which went in favour of the UPA, in the last hours of the prolonged session which three lawmakers of the opposition Bharatiya Janata Party (BJP) flashed wads of currency in the house, alleging they were bribed to abstain from the vote.

Lok Sabha, or lower house, speaker Somnath Chatterjee said he would investigate the charges and would take any action required.

There were strong rumours of attempts to influence lawmakers with money and promises of ministerial berths, election tickets and other bribes by both sides in the days leading up to the trust vote.

"The UPA government may have won the trust vote but the way it was saved was a murder and defeat of parliamentary democracy," Mayawati, chief minister of Uttar Pradesh state and leader of the Bahujan Samaj Party (BSP), said at a press briefing on Wednesday along with leaders of the left and several regional parties.

The 10 parties, which are not aligned to either the UPA or the main opposition National Democratic Alliance (NDA) led by the Hindu right-wing Bharatiya Janata Party
(BJP), announced they would be launching a campaign against the "corrupt" UPA and would be projecting Mayawati, a leader of lower-caste Dalits, as a prospective prime minister.

The UPA's five-year term is scheduled to end in May 2009 and all the parties are gearing up for an election in eight to 10 months.

Communist Party of India-Marxist leader Prakash Karat said the government may have won the trust vote, but had lost the trust of the nation by the "immoral manner" in which it secured a victory.

The Hindu right-wing BJP, which leads the NDA, said it would launch a nationwide agitation against the UPA for corrupting and degrading democratic values. All BJP lawmakers who voted for the UPA or abstained during the confidence motion were likely to be expelled, PTI news agency reported, quoting sources in the party.

Chandra Babu Naidu, leader of the Telugu Desam Party from southern Andhra Pradesh state and a leading constituent of the new third front said the opposition would have won the trust vote if the UPA had not "engineered abstentions" and "manipulated votes."

Naidu said one of his party lawmakers had voted for the UPA while another had abstained. The TDP would take action against these members, he said.

Leading newspapers had banner headlines saying the government's win had been damaging morally and ethically.

"PM wins, parliament plumbs new depths," said the daily Hindustan Times front page headline under the banner of "Shame." "Government sails through but is bruised by vote buying charges," said the Times of India. "Trust wins, but distrust too," said the Economic Times.

Overnight celebrations continued at the headquarters of the Congress Party, which leads the UPA coalition. Senior leaders dismissed the charges of bribery claiming they were trumped up when the opposition felt the UPA would win the trust vote.

Soon after winning the trust motion, the prime minister had said the bribery charges levelled by the BJP lawmakers made him "extremely sad." He said, "Whatever needs to be done under the law (to probe the allegations) will be done." dpa