A navy mine sweeper searched the English Channel Monday for a container with 6 tons of a highly toxic pesticide that could have disastrous effects on marine life if it spills, maritime authorities said.

The minesweeper Le Clio left port early Monday to resume the search for the 40-foot container carrying 100 drums of the pesticide Lindane, lost March 13 when the Indonesian ship The Perintis sank 40 miles northwest of Cotentin.Maritime authorities managed to recover five containers last week, but one was lost when the ropes snapped while a French naval patrol boat towed it toward Cherbourg.

Ecologists fear the container, believed to be at the bottom of the Channel about 231 feet down, could cause widespread damage to marine life if it spills.

A spokesman for the group Greenpeace said such a spill could cause one of the largest ecological disasters on record.

Lindane has been banned or restricted in Japan, the United States and Sweden but is sold freely in other parts of the world, where it is used by farmers, in wood preservative products and in head-lice shampoo.