The Bureau of Land Management (BLM) still has not forced mining companies to restore 20 of 30 western mining sites abandoned at least two years ago, the General Accounting Office has reported.

The GAO, the investigative arm of Congress, said the situation is caused by the bureau's policy of not requiring most companies to post reclamation bonds and the setting of a low priority on getting federal lands restored after mining ends.

The report, identifying 17 sites in Nevada and three in Colorado, was released by Rep. Mike Synar (D-Okla.), chairman of the House Government Operations environment, energy and natural resources subcommittee.

Synar requested the report following an earlier GAO study of six hard-rock mines on U.S. property in Colorado and 24 similar sites in Nevada.

In the 1985-86 study, GAO recommended that the bureau require all mining companies to obtain reclamation bonds. Last April, a bureau task force said bonds should be required on a case-by-case basis because the incidence of unreclaimed mines is relatively low. The latest GAO study renewed the recommendation that mine operators leasing federal land be required to post reclamation bonds.

GAO said that the bureau has taken little action to get mining companies to repair the land.

"In general, BLM officials explained that other land management duties were more important than pursuing the reclamation of these mine sites," the report said. "For the same reasons, BLM officials had no plans to assure the eventual reclamation of these mine sites."

The report said, however, reclamation of three other sites occurred at mining company expense after bureau officials contacted them.

Synar said in a statement that the GAO's latest report demonstrates "the adverse effects of this bonding-over-my-dead-body policy . . . . Despite BLM's assurances of vigorous compliance enforcement, it has failed to take even the most basic steps to obtain reclamation."

Tim Locke, a bureau spokesman, said the agency wanted to see the report before commenting on it.