The Sierra Club and a group of local civic associations asked the federal court in Washington yesterday to block the widening of traffic-clogged I-270 in Montgomery County.

The groups said the $113.5 million project, approved by the Maryland State Highway Administration, violates federal environmental protection laws.

As part of the 16-mile project, the highway will be expanded from six to 12 lanes between North Bethesda and Gaithersburg, and up to six or eight lines as far north as Clarksburg. About 10 acres of Cabin John Regional Park will be used for the highway, the lawsuit says, along with 70 acres elsewhere that now serve as wildlife habitat and wetlands.

Jim Doughtery, spokesman for the Sierra Club's Potomac chapter, called the project a "classic case of sacrificing the public's parkland for a 12-lane boondoggle."

Montgomery officials have pushed for the widening project to spur development along the county's high-technology corridor and to ease daily traffic snarls on its major north-south commuter route.

Plaintiffs in the suit include the North Bethesda Congress of Citizen Associations, the Washington Area Bicyclist Association and the Coalition for Sensible Transportation (COST), composed mainly of homeowners near the highway.