An Indian court on Wednesday summoned former prime minister Manmohan Singh as one of the accused in an investigation into illegal government coal mine allocations, dealing a fresh blow to the ailing Congress party.
Singh, who was India's prime minister from 2004 until last year, is the highest-profile figure to be implicated in the investigation into the allocations, long dogged by suspicions of corruption.
He faces allegations of corruption-related offences, breach of trust and criminal conspiracy, which carries a possible life sentence, the Press Trust of India (PTI) news agency said.
"The court has named him as an accused and asked him to present himself before it," an official from India's Central Bureau of Investigation (CBI) told AFP on condition of anonymity.
The 82-year-old former premier, who enjoyed a reputation for probity during his decade as head of the Congress-led government ousted in last year's general election, has denied any wrongdoing.
Responding to the summons, he said he was open to scrutiny and confident the truth would come out.
"I will be able to establish my total innocence," he said in comments broadcast on the NDTV news channel.
In an earlier statement Singh said he was "upset" but that "these are the facts of life," adding: "I am open to all scrutiny".
India's Supreme Court ruled last year that there were "legal flaws" in the government's procedure for awarding nearly 220 coal blocks in India, which relies on the fuel for two-thirds of its power generation.
- Blow to Congress -
Singh, who also held the coal ministry portfolio while in office, is one of six people accused by the court over the awarding of the Talabira-II coal block in the eastern state of Orissa in 2005.
They include billionaire businessman Kumar Mangalam Birla, whose company Hindalco Industries won the allocation.
Shares in Hindalco dived as much as 7.8 percent on the news to 127.30 rupees ($2.03) before recovering marginally to close at 130.45 rupees.
The company denied that it, or its chairman Birla, had acted unlawfully in securing the mine allocation.
CBI judge Bharat Parashar summoned Singh and the five other accused in the case to appear before him on April 8, PTI said. All face the same charges.
The move to name Singh is a fresh blow for India's Congress Party, which has suffered a series of state election defeats since its disastrous performance in national polls last year.
These included a complete wipe-out in Delhi assembly elections earlier this month in which the upstart Aam Aadmi (Common Man) Party took power.
The CBI launched its investigations after the government auditor in 2012 accused the coal ministry of underpricing coalfields when allocating them to companies, giving away billions of dollars of public money in the process.
India's Supreme Court cancelled all the coal blocks allotments last year and they are now been re-auctioned by the government of Narendra Modi, who succeeded Singh as prime minister last year.
Singh is credited with opening up the Indian economy in the early 1990s and was known as "Mr. Clean", although his public image was dented when a series of corruption cases became public.
Modi's Hindu nationalist Bharatiya Janata Party won a landslide election victory last year on promises to end corruption and kickstart the flagging economy.