Congress spokesman Randeep Singh Surjewala said Vadra has been going through "witch-hunting" for the last 41 months.
He was talking to reporters here on a claim in a media report that Vadra had "links" with fugitive arms dealer Sanjay Bhandari.
"As far as any allegations against Robert Vadra are concerned, we will only say, Modiji has been in power for 41 months.
"They have a government in Haryana andRajasthan, and by all means, conduct any investigation that you choose, and come to a conclusion through a free and fair process of law of any wrong doing," Surjewala said.
More From This Section
"Allegations were levelled in these two states, based on which they came to power," the Congress spokesman added.
A national news channel yesterday had claimed that "the absconding arms dealer Sanjay Bhandari (had) booked business- class tickets for Vadra in 2012."
Citing the media report, the BJP today asked Congress leaders Sonia Gandhi and Rahul to break their "silence" on it.
Addressing a press meet in New Delhi, Defence Minister Nirmala Sitharaman said the silence of Sonia Gandhi and Rahul will be construed as acceptance of the charges against Vadra.
Meanwhile, Times Now and Republic news channels were not allowed by the Congress to cover Surjewala's press meet at the party office here.
Asked why the two channels were barred from covering the press conference, Surjewala said he understood the sentiments of the media but journalism should "show the mirror of truth, not becoming mirror of BJP."
He went on to add, "When you carry out pre-meditated, biased and fixed agenda as agents of the ruling party, then some semblance of journalism dies. Journalism is not about being about Congress or BJP, about being SP or JDU or any other political party. Journalism is about asking me difficult question."
Surjewala was apparently referring to Siddaramaiah today issuing directions for curtailing funding of celebrations to mark the diamond jubilee of Vidhana Soudha, the seat of state legislature, amid reports about a proposal for extravagant celebrations which had raised a controversy.