Pinning down the government on the leakage of the report indicting former External Affairs Minister K. Natwar Singh and his son Jagat Singh, the BJP was on the offensive today in both Houses of Parliament.

While the Speaker sought ‘‘an explanation from the government’’ on how the contents of report appeared in the media before it was tabled in the House, the opposition (that is, BJP aided by Samajwadi Party) levelled corruption charges against Congress president Sonia Gandhi with Leader of the Opposition L K Advani providing the slogan of the day: ‘‘Congress ka lafra hai, Natwar Singh to bakra hai.’’

Opposition members strongly contended that the Congress party, which has been named along with Natwar Singh as a non-contractual beneficiary, could not be let off the hook without strictures.

The agency which will probe the leak will be “decided in a day or two,” said Parliamentary Affairs Minister Priya Ranjan Dasmunsi. He said that a TV channel (CNN-IBN) began broadcasting on the report ‘‘even before the sealed envelope had reached the Prime Minister’s Office.”

“The PM himself is yet to see (that is read) the report,’’ Dasmunsi said. As per procedure the PMO sent the ‘‘sealed envelope’’ to Finance Minister P. Chidambaram. And, Chidambaram, in turn, said, he’s ‘‘yet to open the envelope’’.

It is the Finance Ministry which is expected to submit the ‘Action Taken Report’ on Pathak’s findings and submit it to the Cabinet before tabling it in Parliament. ‘‘The ATR will be prepared soon—faster compared to any other report (ATR) tabled in Parliament. The Finance Minister has assured (us),’’ Dasmunsi said.

Dasmunsi, along with UPA allies and Left partners, held a press conference targeting the BJP for what they called ‘‘motivated disruptions aimed at monopolising House proceedings and undermining the parliamentary system of democracy’’.

CPI member Gurudas Dasgupta went to the extent of calling the BJP-led disruption of the House as ‘‘parliamentary fundamentalism’’.

Cornered from all sides, Natwar Singh himself pledged his loyalties to the Congress party even as the Delhi High Court today rejected a plea for not making public the Justice Pathak report.

The court was hearing a plea by Jagat’s friend Andaleeb Sehgal, who was found by the Pathak panel to have got a share in the money out of the sale of oil contracts.