Environmentalists sued the federal government Thursday over plans to log in central California's Giant Sequoia National Monument (search), home to two-thirds of the world's largest trees.

The Sierra Club (search) and four other environmental groups called the U.S. Forest Service's decision to include widespread logging in its plan for managing the 327,769-acre monument a scientifically suspect strategy meant to satisfy timber interests under the guise of wildfire prevention.

"This plan opens up huge areas to logging and specifically targets trees big enough to sell, undermining the whole purpose of the monument," said Carla Cloer of the Tule River Conservancy (search), one of the organizations challenging the federal plan.

The lawsuit filed Thursday in San Francisco federal court seeks to block the plan and have it vacated.

Forest Service spokesman Matt Mathes said the agency's plan to allow "thinning" of some trees in Sequoia was motivated by fire prevention goals and does not permit commercial logging.

Only trees with diameters of up to 30 inches can be cut under the rules.

The giant sequoia commonly grows to 30 feet in diameter, Mathes noted. Timber companies will pay the government for the right to remove some of the larger trees that fall within the 30-inch limit, which will provide money for removing brush and smaller trees that could pose a fire danger, he said.

President Clinton created the monument in April 2003.

Logging interests, recreational groups and Tulare County unsuccessfully sued to eliminate the designation, contending Clinton exceeded his authority when he acted to protect 38 ancient groves of the giant trees within the 1.1 million-acre Sequoia National Forest.

The groves account for about 20,000 acres, or roughly 6 percent, of the monument's total acreage.