Indian police have attacked protesters observing the 27th anniversary of the world's worst industrial accident.

Police armed with sticks attacked the demonstrators Saturday in Bhopal, where a Union Carbide pesticide plant leaked lethal gas in 1984, killing thousands of people and maiming thousands more.

The protesters, who were attempting to block rail lines, pelted the police with stones.

Bhopal rights activists say they staged the demonstration to demand more compensation for survivors of the accident and to protest Dow Chemical's sponsorship of the 2012 London Olympics.

Dow bought Union Carbide years after the chemical accident and paid India $470 million for Bhopal victims. Bhopal victims' rights groups say the government should have demanded a larger compensation package.

Dow insists disaster liabilities have been resolved.

Shivraj Chauhan, the chief minister of Madhya Pradesh state, where Bhopal is located, has urged India not to attend the London Olympics to protest Dow's sponsorship of the event.

The Associated Press reports organizers of the London Games have said they will not change their position on Dow's sponsorship.