Anand Sharma said that there will be global ramifications of the "scam of the century".
Intensifying its attack over the raging Rafale controversy, the Congress on Sunday accused Prime Minister Narendra Modi of violating the oath of secrecy by revealing details of the new deal to an industrialist who subsequently became an offset partner instead of Hindustan Aeronautics Limited.
Hours after Finance Minister Arun Jaitley again came out in defence of the deal for purchasing 36 French fighter jets, Congress Spokesperson Anand Sharma demanded that the Prime Minister respond to the allegations directed at him.
"The question to the Prime Minister is -- how this information came out that he will go go to France and reverse the deal?" said Mr Sharma referring to PM Modi's April 2015 announcement of an intergovernmental deal to purchase 36 jets instead of 126 being negotiated during the erstwhile UPA regime.
"Then Foreign Secretary S. Jaishankar had said that the Rafale deal was not on the agenda during PM Modi's visit to France. Nobody knew as to PM Modi's visit to France and the announcement of a new deal. Even the Cabinet Committee on Security, the Indian Air Force, the Cabinet or the Foreign Secretary were not aware about the decision.
"Direct allegations are against the Prime Minister that he violated his oath of secrecy. Only he and none else could have revealed to the private company that he will reverse the deal," said Mr Sharma while pointing to the incorporation of Reliance Defence Limited just days before PM Modi visited France in April 2015.
"It's a conspiracy, only one (Modi) person with knowledge about the new deal -- without telling anyone in the Cabinet, or the Ambassador etc -- revealed the details to the industrialist and asked him to form a company," alleged Mr Sharma.
He said that there will be global ramifications of the "scam of the century".
"We had warned the Prime Minister that this scam will have global ramifications. It will not be limited to geographical boundaries of India but resonate in the world capitals, and that is what is happening," said Mr Sharma.
The Congress leader was referring to French media reports on former France President Francois Hollande's claims regarding a private Indian firm becoming an offset partner in the intergovernmental deal for the fighter jets.
"Why is the Prime Minister silent? He speaks on every subject, he is the main campaigner for the BJP and the government. So when the allegations are against him, it's he who should answer, and not others on his behalf," said Mr Sharma.
The Congress leader dismissed as "repeated lies" the latest defences and justifications given by Mr Jaitley and Defence Minister Nirmala Sitharaman on the matter.