Firing a fresh salvo at Prime Minister Narendra Modi over the Rafale deal, Congress president Rahul Gandhi alleged on Thursday that he was a "corrupt man" who helped Anil Ambani pocket Rs 300 billion in the purchase of the fighter aircraft.
Gandhi demanded an investigation against the prime minister.
The Congress president also described Defence Minister Nirmala Sitharaman's trip to France as part of a "huge cover-up" by the government.
His attack at the government came a press conference following a report in the French media that Dassault Aviation, the manufacturer of Rafale, had to choose Ambani's firm Reliance Defence as its offsets partner in India as a trade-off for getting the deal.
The government has been insisting that it had no role in the Dassault's choice of Reliance Defence.
Dassault Aviation said in a statement that it has "freely chosen to make a partnership with India's Reliance Group".