Shares of Indian wireless carriers plunged on Thursday after the country’s top court rejected the firms’ request to re-calculate about $13 billion of past dues that they owe to the government.

The Supreme Court on Wednesday dismissed a plea from telecom companies to re-compute Adjusted Gross Revenue (AGR) dues, marking a significant blow to firms already grappling with financial strain.

The Supreme Court has denied Vodafone Idea and Bharti Airtel's curative petition seeking a re-calculation of adjusted gross revenue (AGR) dues totaling over Rs 1 lakh crore. The companies are required to pay the amount by March 31,

Curative petitions are rare and generally considered only when there is substantial miscarriage of justice,” said Ankit Rajgarhia, principal associate, Karanjawala & Co. Cash-strapped Vodafone had reported a debt of Rs 2.