BANGOR – A car manufacturers’ group filed a lawsuit in federal court Tuesday in an effort to stop the state from enforcing a new law to facilitate recycling of mercury switches from junked automobiles.

The suit filed in U.S. District Court by the Alliance of Automobile Manufacturers calls Maine’s law an illegal restriction of interstate commerce.

The law, which takes effect in 2003, requires automakers to pay $1 bounties to junkyards and scrap dealers to remove the switches. Automakers also have to set up consolidation centers to collect the switches, and package and ship them to recyclers.

Alliance President Josephine Cooper called the Maine law “an attempt to discriminate against out-of-state businesses.” But Cooper said the alliance, which represents a dozen car and light-truck manufacturers, is willing to discuss alternatives to the Maine law that would address the same concerns.

The alliance also noted that automakers have stopped putting mercury switches in new cars.

The law was a legislative priority of the Natural Resources Council of Maine during this year’s legislative session. The council’s advocacy director on Tuesday said he believes the suit is frivolous and that the court will uphold the law.

The council’s Pete Didisheim also said the auto group raised similar concerns during the legislative session, but a review of the proposal by the state Attorney General’s Office concluded that the bill was legally sound.

Didisheim said the manufacturers promised more than a decade ago to put mercury-free switches in new cars, but are only getting around to it with this year’s models.

The council estimates that 1,500 pounds of mercury remain in switches in all of the cars registered in Maine. It says mercury can get into the environment when cars are scrapped, shredded and smelted. Mercury exposure can cause a variety of ailments, including kidney and nerve damage and mental problems.

Maine’s mercury switch recycling law is among the latest in a series of steps taken by the state to prevent contamination.

Another recently enacted bill phases out the sale of mercury thermostats used in residential and commercial buildings by 2006. Last year, lawmakers banned the sale of mercury fever thermometers, and in 2000, required labeling and recycling of mercury products and banned their disposal in trash.

Maine hospitals, hoping to remove mercury from their waste by 2005, have offered mercury-free digital thermometers to their employees.