The opposition asked the government's Central Bureau of Investigation to refer the two-decade-old case to the Supreme Court, the Financial Times reported.
A New Delhi court Thursday dismissed charges of conspiracy to cheat the Indian government in the purchase of the Swedish howitzers. The decision freed the three European-based Hinduja billionaire brothers who had been accused of involvement in the scandal.
The scandal surfaced during the term of the late Prime Minister Rajiv Gandhi, head of the Congress party, which is now led by his Italian widow Sonia.
Gandhi was accused of accepting illegal kickbacks in the purchase of the howitzers. Last year, he was posthumously cleared of any wrongdoing in the deal.