The cable from a US Embassy official said a Congress party functionary showed him two cases full of cash meant to bribe lawmakers to vote with the party on the nuclear deal.

Angry opposition lawmakers waved wads of cash in Parliament and called for Prime Minister Manmohan Singh’s resignation. An Indian newspaper published the diplomatic cable alleging that the Congress party paid $2.5 million each to at least four lawmakers to buy their support.

“This government has no authority to continue. It must resign immediately,” Arun Jaitley of the right-wing Bharatiya Janata Party told reporters.

The Congress party member accused of bribing the lawmakers has denied the allegations.

The nuclear deal, ratified by parliament in 2008, ended more than three decades of nuclear isolation for India. It calls for opening of India’s civilian reactors to international inspections in exchange for the nuclear fuel and technology it has been denied by its refusal to sign the Nuclear Nonproliferation Treaty.

The uproar comes amid a wave of scandals that have hit Singh’s government in recent months.

The entire last session of Parliament was paralyzed by opposition demands for a probe into a multibillion-dollar telecommunications scandal. Singh initially refused to allow an investigation, but subsequently bowed to opposition pressure and accepted the demand.

Former Telecoms Minister A. Raja has resigned and is now in jail pending an investigation into the irregular sale of cell phone spectrum in 2008 that reportedly cost the government tens of billions of dollars.

In a new twist to the case, a businessman who had been questioned by investigators over his involvement in the telecoms scam was found dead in the southern city of Chennai after apparently committing suicide Wednesday.

Though the government faces no immediate threat, the scandals have dominated Indian politics for months at a time when Singh has sought to present the country as a rising international power.