The Bharatiya Janata Party (BJP) accused Congress of giving a political colour to the process of investigation that involves AgustaWestland's middleman, James Christian Michel on Sunday.
They said that the anxiety of the opposition party is evident in its behaviour in the case.
BJP Spokesperson Sudhanshu Trivedi, while talking to reporters, sought to know from the Congress that why all the foreign nationals accused in corruption cases in India had links with the "first family" of the opposition party.
"The people who make a hue and cry for inquiries into all economic matters are now working in the rescue of a foreign national who is involved in corruption. Your (Congress') anxiety is evident," Trivedi said, pointing towards a slip of paper being passed by Michel to his lawyer Joseph in the ED custody which referred to a set of questions related to Mrs. Gandhi.
Condemning the Congress for giving the questioning of Michel by investigative agencies a "political colour", he said: "Let it be examined, everything would be clear in the AgustaWestland case."
The BJP leader accused the Congress of giving a "cover fire" to Michel and trying to protect him.
"Why is it so that all the foreign nationals accused in corruption cases in India have links with the first family of the Congress," he asked.
Earlier, the Congress alleged the Modi government was the benefactor and supporter of AgustaWestland, the helicopter manufacturing company involved in VVIP chopper deal, and said it was trying to suppress the truth by hiding behind the Enforcement Directorate.
The ED on Saturday brought in the name of 'Mrs. Gandhi' and 'big man R', an apparent reference to Sonia Gandhi and her son Rahul Gandhi, in a special court when it got a seven-day extension of custody of British national Christian Michel, the alleged middleman in the deal.
During arguments, ED counsel L.D. Singh also referred to Michel saying "big man 'R', son of an Italian lady who is going to be the next Prime Minister in communication between Michel and AgustaWestland," an apparent reference to Congress President Rahul Gandhi.