The BJP fielded Defence Minister Nirmala Sitharaman to counter the Congress charge that the scam took place in 2017 under the Modi government when the letters of understanding were signed by the Punjab National Bank in favour of Nirav Modi.
She said Nirav Modi may have been able to run away from the country, but the government is taking action against him.
"We are not conspiring to help scamsters flee the country, the BJP government is catching them instead," she told reporters.
She accused the Congress of spreading lies on the issue.
Sitharaman also alleged that it was Congress leader Rahul Gandhi who attended a promotional event hosted by Nirav Modi.
She also cited the example of a government director of Allahabad Bank, who in 2013 had raised objections to the financial restructuring of Gitanjali Gems, saying he was asked to resign and his dissent was not even recorded.
Central probe agencies CBI and ED yesterday continued their crackdown in the Rs 11,400-crore bank fraud case involving Nirav Modi and family, registering a fresh case against his maternal uncle Mehul Choksi,
The CBI has alleged that the new FIR pertains to 143 LOUs worth over Rs 4,886 crore fraudulently issued to three companies of Choksi -- Gitanjali Gems, Nakshatra and Gili -- during the period 2017-18, officials said.
The agency had earlier registered a separate case involving Rs 280-crore fraud, which has now been expanded to cover LoUs worth Rs 6,498 crore issued to accused companies of Nirav Modi and Choksi.
An LoU is a letter of comfort issued by one bank to branches of other banks, based on which foreign branches offer credit to buyers.