Bhopal | Four organisations working with survivors of the 1984 Bhopal gas tragedy have expressed grief over the death of internationally acclaimed photographer Raghu Rai, saying his images ensured the truth of the disaster could not be buried.

He captured the immediate and unbearable human cost of the tragedy and returned, time and again, "to reveal the long arc of suffering, official neglect, and the determined resistance of survivors seeking accountability," they said.

Rai, 83, one of India's best-known photographers who distilled the essence of an evolving India and its people through his lens, died at a private hospital in New Delhi on Sunday.

The prolific photographer, a protege of Henri Cartier-Bresson, shot some of the most significant events in Indian modern history, including the Bangladesh refugee crisis of 1972 and the Bhopal gas tragedy of 1984.

His pictures have been etched into India's collective memory. One of the most haunting images that came out of the Bhopal disaster is that of an infant, eyes open forever in a cold dark gaze, as a hand caresses the child into an eternal slumber.

A total of 5,479 people were killed and more than five lakh were affected physically following a toxic gas leak from the Union Carbide factory in Madhya Pradesh's capital on the intervening night of December 2 and 3 in 1984.

In a statement on Sunday, Bhopal Gas Peedith Mahila Stationery Karmchari Sangh, Bhopal Gas Peedith Mahila Purush Sangharsh Morcha, Bhopal Group for Information & Action and Bhopal Gas Peedit Nirashrit Pensionbhogi Sangharsh Morcha mourned Rai's death.

"We mourn the passing of eminent photojournalist Raghu Rai, whose images ensured that Bhopal's truth could not be buried," the statement said.

"Raghu Rai was a steadfast ally of the Bhopal campaign. He captured the immediate and unbearable human cost of the December 1984 Union Carbide disaster and returned, time and again, to reveal the long arc of suffering, official neglect, and the determined resistance of survivors seeking accountability," said Balkrishan Namdev of Bhopal Gas Peedit Nirashrit Pension Bhogi Sangharsh Morcha.

Raghu Rai did not photograph a past tragedy-he showed an ongoing disaster, where he came back to Bhopal years later to document the disabilities in the children born to the gas-exposed parents, Bhopal Gas Peedit Mahila Stationery Karmchari Sangh representative Rashida Bee said.

"His images made it impossible to separate the human suffering in Bhopal from the responsibility of Union Carbide and Dow Chemical," Rachna Dhingra of Bhopal Group for Information & Action added.

The NGOs extended their heartfelt condolences to Rai's family and to all those who were moved by his work