SAN FRANCISCO (AP) _ Pioneering environmentalist David Brower has quit the Sierra Club's board of directors, accusing the group of fiddling while the world burns.

Brower, 87, one of the century-old environmental group's most charismatic and respected leaders, said Thursday the organization's officials have lost their zeal.

``The world is burning and all I hear from them is the music of violins,'' Brower said. ``The planet is being trashed, but the board has no real sense of urgency. We need to try to save the Earth at least as fast as it's being destroyed.''

Brower, who joined the club in 1933 and was its first executive director, said the club is not responding to such issues as overpopulation, immigration, mass transit and wilderness preservation.

``Overpopulation is perhaps the biggest problem facing us and immigration is part of that problem,'' he said. ``It has to be addressed.''

Brower, a seminal figure in the U.S. environmental movement, led the group in the '50s and '60s. The board removed him in 1969 after members complained about his often strident views and lack of consultation on crucial decisions.

Brower went on to found Friends of the Earth and the League of Conservation Voters. Both now rank among the nation's most respected and powerful environmental groups.

He was subsequently re-elected to the Sierra Club board in 1983, 1986, 1995 and 1998.

Sierra Club President Carl Pope said he was sorry to see Brower go.

``We'll miss him, but at the same time, this is a large organization, with 600,000 members, 63 chapters and dozens of committees,'' Pope said. ``None of us agree with everything the board does _ including me.''