Background: A U.S. appeals court had reinstated some of the claims against the unit of Dow Chemical Co. stemming from the world's worst industrial accident, which killed more than 6,000 people. U.S. District Judge John Keenan, who had dismissed the class-action suit in 2000, ruled that the 1999 suit was filed too long after the accident and the groups that sued had no legal standing to bring the action.

"Locating thousands of people who have resided 8,000 miles away in Bhopal, India, over a span of more than 30 years would be nigh impossible," Keenan said in a 23-page ruling, rejecting a request that he order medical monitoring in the Indian city.

Union Carbide, which Dow Chemical bought in 2001, paid India $470 million in 1989 in an out-of-court settlement over the accident. An Indian court last summer said Union Carbide's former chairman, Warren Anderson, must face criminal charges of culpable homicide in connection with the accident.

"Union Carbide has met its obligations to clean up the contamination in or near the Bhopal plant," Judge Keenan said.

"Having sold their shares long ago and having no connection to or authority over the plaint, they cannot be held responsible at this time," he added.