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Hours after suspected methane gas killed at least 15 workers inside an NHPC hydropower project tunnel in Sikkim, a father-and-son duo died after inhaling toxic fumes in an alleged illegal coal mine in eastern Assam’s Tinsukia district.

A rights body in the district said Sagar Ali and his son Ishan Ali died after inhaling gas emitted as a consequence of the allegedly illegal coal mining in the Ledo area. The incident happened on the night of July 20.

The district police, however, said the cause of death remains to be ascertained. “The matter is under investigation,” a senior officer said on Wednesday (July 22, 2026).

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The deceased were from Gaibandha village in the Jaleswar area of southwestern Assam’s Goalpara district, the Tinsukia District Committee of the International Human Rights Council (IHRC) said.

Abandoned coalfield

“According to our investigation, the alleged illegal rat-hole mining operation is in an area known as Deep Mine, located on land abandoned by the North Eastern Coalfields,” L. Ratan Singh, the general secretary of the IHRC district committee, said.

North Eastern Coalfields is a specialised operation unit managed by Coal India Limited.

Mr. Singh also said his organisation identified the owners, supervisors, and the operator of the mine, as well as the mastermind of the illegal coal entry system codenamed ‘Big B’.

He urged the district authorities to crack down on the illegal coal mining activities and conduct a comprehensive, impartial probe into the deaths of the father and son, reportedly engaged as miners in the Deep Mine area.

The IHRC unit has also appealed to the Gauhati High Court to take suo motu cognisance of the incident and initiate appropriate proceedings. “No person should lose his or her life in the future as a result of such illegal mining,” Mr. Singh said.

At least 10 miners have been killed in allegedly illegal coal mines between September 2022 and June 2024. They were either trapped in “rat-hole” mines that collapsed or were exposed to toxic gases.

“Rat-hole” mining is an unscientific and hazardous method of coal extraction employed in the hilly areas of Meghalaya, Assam, Arunachal Pradesh, and Nagaland. It involves digging narrow, deep vertical shafts and horizontal tunnels, often just large enough for one person to crawl into, where miners scrape or hack out coal using primitive tools.

Published - July 22, 2026 10:45 pm IST