At least 54 miners were feared dead in eastern India after the roof of a coal mine collapsed following an explosion.
"This is an unprecedented situation and the chances of their survival are zero," the chairman of Bharat Coking Coal said.
The incident took place in the Dhanbad district of the eastern state of Jharkhand late on Wednesday.
As many as 57 miners had gone inside the mine located in the western Jharia area, about 105 miles north of state capital Ranchi, when an explosion to open up a new mining area caused the roof collapse, releasing deadly methane gas, an official said.
"The miners were working at a depth of 460 metres when the explosion and the gas leak reduced the oxygen level to almost zero," he said.
Three miners who were rescued complained of severe breathlessness.
Every year, hundreds of miners get trapped inside mines in India, where safety standards are seldom met by authorities.