Vedanta Resources has been ordered to permanently close its Tuticorin copper smelter in India, where anti-expansion protestors were killed by police earlier in May.
The FTSE 250 mining group said the state government of Tamil Nadu told its pollution control board to seal the smelter and shut the plant for good.
Vedanta said: "We are further studying the order and shall keep the stock exchanges updated on any developments." A government minister suggested there was no chance of the plant reopening.
Vedanta stopped production at the plant at the end of March for maintenance but the shutdown was extended when the Tamil Nadu State Pollution Control Board withdrew its consent to operate. On 22 May more than three months of protests against a planned doubling of capacity culminated in police shooting dead 12 or more protestors.
The next day the Madras High Court ordered Vedanta to stop construction works on the project and for authorities to hold public hearings before granting environmental approval to the construction. The smelter, which is run by Vedanta's Sterlite Copper unit, is controlled by Vedanta Ltd, a subsidiary of Vedanta Resources.
Opponents of the expansion plan in the city of Tuticorin, whose Indian name is Thoothukudi, have said the plant is a major source of pollution and a risk to fisheries. The smelter has been shut down several times due to pollution complaints, and in 2013, it was fined £10m for breaching environmental norms and operating without consent from the state pollution board.
The government order endorsed the pollution board's earlier statement that the plant should be closed to "protect and improve the environment" and the wider public interest, India's Economic Times reported.
"The decision to close the plant was arrived at upon consideration of the interests and sentiments of the people of Thoothukudi," chief minister Edapaddi Palaniswami told reporters in Chennai. He dismissed the prospect of a legal case by Vedanta against the government order as "imaginary."