A court in Bhopal, India has sentenced seven men to two years each in jail after finding them guilty of criminal negligence over the accident that spewed tonnes of poisonous gas from a Union Carbide India Ltd plant in 1984.

These are the first convictions related to the Bhopal gas accident, which is estimated to have caused the deaths of at least 15,000 people.

Activist groups say they will appeal to higher courts for larger penalties for the seven, who include 85 year old Keshub Mahindra, who then headed the company. They are also pushing for the extradition from the US of Warren Anderson, former head of Union Carbide.

“This is a typical delayed Indian justice. We are very upset,” engineer and Bhopal resident Ramaswamy Venkatachalam told the BBC. “A two-year sentence is no justice when so many people died. Letting off Warren Anderson angers us more than the 25-year delay.”