Ongoing efforts to reach victims of a mining disaster in the northeast have exposed what campaigners say is poor enforcement against such illegal mines, where undocumented workers risk injury or death.
At least 15 people were trapped when an illegal coal mine in Meghalaya state flooded on Dec. 13. Rescue efforts continue, although relatives said this week they had lost hope that the miners were still alive.
Environmental concerns have led to India imposing bans on the mining of coal, mica and sand, among other minerals. Yet, workers across the country continue to put themselves at risk as illegal mining continues.
"A ban does not mean you close your eyes to (mining). It means you physically protect (natural resources) in some way," said Sumaira Abdulali, founder of the environmental advocacy group Awaaz Foundation.
"But we never set systems in place. We would prefer for things to remain invisible."
The most recent disaster highlighted the dangers of so-called "rat-hole" mines, where workers crawl into narrow shafts on bamboo ladders to extract low-quality coal.
In Meghalaya, campaigners estimate that 5,000 rat-hole mines continue to function despite a ban imposed in 2014 by India's environmental court, the National Green Tribunal (NGT).
India's courts have ordered bans on mining various minerals, but it is up to state authorities to enforce them, according to Niranjan Kumar Singh, a joint secretary in the mining ministry.
"The role of states has become important as the centre's role is in policy making," he said by phone. "We do not have the machinery to monitor or regulate."
But Teining Dkhar, commissioner of Meghalaya's mining and geology department, said his state has no "regulatory mechanism" to enforce bans on illegal mining.
"Only when we give a licence for mining, we ensure that all environmental and labour laws are followed," he said by phone on Friday.
Illegal mining tends to attract workers from around India and neighbouring countries who are lured by the promise of relatively high wages, but are faced with dangerous conditions once they arrive.
Workers in the coal mines are promised about 2,000 rupees ($28.46) per day - more than 10 times the average Indian daily wage, said Angela Rangad of Thma U Rangli-Juki (War of the Oppressed), a collective of democracy and human rights groups.
"They think they will work a few days and return. But they are never paid on time and remain trapped as they keep waiting for their wages," said Rangad.
Other workers - including children - are trafficked.
When the anti-trafficking charity Impulse NGO Network surveyed rat-hole mines in Meghalaya between 2007 and 2013, it found 1,200 children, many of whom were trafficked from Nepal and Bangladesh.
India is one of the world's most dangerous countries to be a coal miner, with one miner dying every six days on average in 2017, according to government data.
The number is likely even larger, as deaths in illegal mines are common but often go unreported, according to campaigners.
A 2017 Thomson Reuters Foundation investigation in Maharashtra state found that workers were drowning as they illegally extracted sand from the bottom of a creek near Mumbai, India's commercial capital.
The deaths were not reported and employers paid only a few families a small amount of money.
In response to the revelations, the Maharashtra state government promised to end illegal mining along the creek, impose regulations, and provide alternate jobs.
But a year later, sand mining was continuing and most of those promises remained unfulfilled.
Campaigners said state governments need to draw up protocols on how to monitor and enforce bans against illegal mining, while the central government must follow up as well.
"If the state fails to take action, the centre should intervene to check the negligence and apathy," said Hasina Kharbhih, founder of the Impulse NGO Network, whose petition against rat-hole mines led the NGT to ban them in Meghalaya.