Leader of Opposition Lal Kishenchand Advani on Thursday demanded filing of a Central Bureau of Investigation case against former external affairs minister Natwar Singh and Congress party in the oil-for-food scam and that Sonia Gandhi [Images] should also be questioned.

"Like others connected with the oil-for-food scam, Sonia Gandhi should also be questioned," he told reporters, on the 17th day of his Bharat Suraksha Yatra in Indore.

• Volcker Report

Referring to Natwar Singh's reported statement that he was being made a scapegoat in the scam, he said neither Prime Minister Manmohan Singh [Images] nor Sonia had so far broken their silence on the Congress being separately mentioned by the Volcker report as a non-contractual beneficiary of the programme.

Their "silence could only be construed as admission of guilt," he observed.

"It is now clear that, having made Natwar Singh a scapegoat, the Congress wants to put a lid on its own involvement in the scandal," he alleged.

Seeking registration of a CBI case against Natwar Singh and the Congress under the Foreign Contribution (Regulation) Act and the Prevention of Corruption Act, Advani said such a move would enable the CBI to send letters to Swiss and other foreign governments to track the money trail and pinpoint the end beneficiaries.