An Indian court has handed down the first criminal convictions in connection with the Bhopal gas tragedy that killed thousands of people more than 25 years ago.

tp-bhopal-justice-cp-881365

Survivors hold posters as they wait for the verdict at Bhopal court in Bhopal, India, on Monday. ((Prakash Hatvalne/Associated Press))

Early on Dec. 3, 1984, a pesticide plant run by Union Carbide leaked roughly 36 tonnes of deadly methyl isocyanate gas into the air in the city of Bhopal in central India, quickly killing as many as 4,000 people.

The lingering effects of the poison raised the death toll to about 15,000 over the next few years, according to estimates.

On Monday, an Indian court convicted seven former senior employees of Union Carbide's Indian subsidiary of "death by negligence" for their roles in the Bhopal gas tragedy.

The former employees, many of them in their 70s, were sentenced to two years in prison and ordered to pay fines of roughly $2,100 US apiece. All seven were released on bail shortly after the verdict.

Large groups of survivors and relatives, along with rights activists, gathered in the city and chanted slogans saying the verdict was too little, too late.

India's Central Bureau of Investigation had originally accused 12 defendants: eight senior Indian company officials; Warren Anderson, the head of Union Carbide Corp. at the time of the gas leak; the company itself and two subsidiary companies.

Seven of the eight Indian company officials were convicted Monday. The other one has since died. Anderson and Union Carbide have never appeared in court proceedings.

Union Carbide, which was later purchased by Dow Chemical Co. settled with the Indian government for $470 million US.

Dow says the legal case was resolved in 1989 when Union Carbide settled, and that all responsibility for the factory now rests with the government of the state of Madhya Pradesh, which now owns the site.

With files from CBC News