Bharatiya Janata party (BJP) leader Subramanian Swamy on Wednesday said the criminal case behind the AgustaWestland VVIP chopper deal would be made clear during the discussion in the Rajya Sabha.

"The case will be made out. So far, facts have been floating. The fact is the whole thing fits into a criminal case. What is that criminal case.that will be made clear today," Swamy told ANI.

"There is short duration discussion today after lunch. Manohar Parrikar will make the statement today. He is a studious person and he won't make any statement unless there is something important to say. He is bound to digest all these Italian High Court's judgments and CAG reports and so on in a way which ordinary people can understand," he added.

A short duration discussion on the issue is slated to take place this afternoon the Rajya Sabha, which is likely to witness a verbal war of words between the BJP and Congress.

The Congress may depute former defence minister A.K. Antony or even former prime minister Dr. Manmohan Singh to counter the charges from the treasury benches.

Parrikar, who met Prime Minister Narendra Modi yesterday, is expected to address the Rajya Sabha at 2 p.m. during the short duration debate.

Parrikar had earlier on Monday said that his address in the Parliament would include how and when necessary clauses or provisions were relaxed to suit the company.

Leader of the Congress in Lok Sabha, Mallikarjun Kharge, has accused the Centre of pursuing a politically motivated campaign to defame the grand old party through the AgustaWestland copter scam.

Meanwhile, former Indian Air Force chief S.P. Tyagi is being grilled for the third consecutive day by the Central Bureau of Investigation (CBI) at its headquarter here in connection with alleged irregularities in the Rs. 3600 crore VVIP chopper deal.

As per reports, the former IAF chief is said to have told the CBI yesterday that he met senior officials of Finmeccanica, the parent company of AgustaWestland, while negotiations for the purchase of VVIP choppers were going on.

He also told the interrogators that he had met Finmeccanica's Chief Operating Officer Georgio Zapa in New Delhi on February 15, 2005.

The CBI yesterday quizzed the former IAF chief on the four firms which he and his wife set up after his retirement from service.

Tyagi, who retired in 2007, has told the CBI that he travelled to Florence, Milan and Venice in Italy in 2008 and 2009 after his retirement.

Tyagi has so far rubbished the allegations levelled against him, saying the change in specifications was a collective decision in which senior officers of the IAF, SPG, NSA and other departments were involved.

The former IAF chief's cousins have also been called for questioning later this week.

Tyagi has been accused in Italy and India of helping AgustaWestland win the chopper contract by reducing the flying ceiling of the helicopter from 6,000 metre to 4,500 metre.

The CBI registered a case against the former IAF chief along with 13 others, including his cousins and European middlemen, in March 2013.

The investigating agency had earlier on Saturday quizzed former IAF deputy chief J.S. Gujral in connection with this case.