It's 25 years since the world's worst industrial disaster struck Bhopal, a town in central India. On 3 December 1984, a toxic leak in Union Carbide Corporation's factory unleashed 40 tonnes of lethal gas into the sleeping town. It killed 3,500 people instantly and an estimated 20,000 have died from complications since. According to activists, the actual figures are much higher.

The compensation paid by Union Carbide to the Indian government was laughably low: nowhere near enough to pay for the actual numbers of people affected by the gas spill. For victims, getting the money from the government proved a Sisyphean task. For those who did manage to obtain compensation, the measly amount quickly ran out in the wake of new or persistent medical complications, hospital bills, and economic problems compounded by disabilities. Many have still not been paid.

Worse, the factory remains a contaminated site, its ruins full of toxic waste, its soil rife with mercury, lead, nickel and other metals, its secretions polluting water for miles around. And nobody wants to clean it up. Dow Chemical, which bought Union Carbide eight years ago, denies culpability and the state is eager to prove that the factory site is no longer harmful. As the novelist Indra Sinha has pointed out, Dow and the State are cosy colluders in this sordid saga. Meanwhile, the people of Bhopal are still suffering the effects: skin disease, deformed babies, contamination of soil, plants and animals.

Earlier this month, in a bizarre form of disaster tourism, the government of Madhya Pradesh (the state in which Bhopal lies) announced they would commemorate the 25th anniversary by opening the factory gates for two weeks, in an effort to show the site is safe. They wanted to display "that the 350 metric tonne waste lying in the factory is not at all harmful," as Babulal Gaur, minister for Bhopal gas tragedy relief and rehabilitation, told newspapers recently.

People closer to the ground – and the truth – were outraged. For a quarter of a century, the people of Bhopal have been fighting to get what is their due: adequate medical care, compensation, employment opportunities and a clean environment. They have had to protest, stage demonstrations, cry and wait. Outside courts, outside government buildings, outside ministerial residences and Dow Chemical offices. Twenty-five years is a long time to be stuck in the one horrible moment when life turned itself inside out. The government's latest attempt to deny the truth is not entirely unexpected but it does sink to new levels of subhuman behaviour. It's small relief that they have not acted out the absurd plan yet.

On 3 December, there will be memorial functions across our capital – lots of singing, candle-lighting, swaying with hands on hearts and so on. Then it'll be business as usual for most. For the people of Bhopal, though, the battle will have to go on. The least we can do is remember, and extend our support to them.