A special court in India on Wednesday summoned former Prime Minister Manmohan Singh to face corruption charges related to the sale of coal fields under his government.
Judges ordered Singh and five others in the case to appear on April 8.
The government sold more than 200 coal blocks during Singh's time, but India's national auditor said in 2012 that awarding the contracts without competitive bidding cost the government billions of dollars. The supreme court ruled last year the process was illegal.
The charges are part of a string of corruption allegations to hit the Congress party-led government during Singh's time as prime minister, which also included auditors reporting $40 billion in losses in the sale of mobile phone licenses and widespread graft during the 2010 Commonwealth Games.
Congress Party spokesman Manish Tewari said "the former government has absolutely nothing to hide" and that they conducted themselves with utmost transparency.
Singh was prime minister from 2004 until last year. He was repaced by Narendra Modi of the Bharatiya Janata Party.
Modi issued an executive order to re-auction the fields in a process key to reducing India's dependence on coal imports. He needs to pass legislation to make the decree permanent.
Auctions of the first 32 blocks have brought in a projected $32 billion, Coal Secretary Anil Swarup told Reuters.
The summons relates to the allocation of a coal field in 2005 to Hindalco Industries, part of the $40 billion Aditya Birla Group. Kumar Mangalam Birla is the chairman of the group. The company declined to comment.
Shares in Hindalco, an aluminum company, fell by 5 percent to their lowest in nearly a year — extending falls over the past week to nearly 20 percent.
Modi, who promised a "Congress-free India" in his election campaign, was visiting the Seychelles as news of the summons broke, posting photos on Facebook of the tropical islands.
Portions of this report are from Reuters.