Russia should provide broader access to its sites containing nuclear or biological material if a U.S. program to keep such material out of the hands of terrorists is to be successful, says a congressional report.

The report by the General Accounting Office says that nearly two-thirds of Russia's nuclear material and many of the locations holding dangerous pathogens once used in the country's bio-weapons program may be inadequately protected.

It noted the United States has spent $1.8 billion over the last decade to help Russia improve safeguards at sites where nuclear materials and warheads are stored, and to help nuclear scientists shift to a post-Cold War economy.

But the report said in many cases progress has been stymied because Russia continues to bar U.S. officials from many of the sites, despite a more liberal access agreement reached in September 2001.

"Russia is not providing needed access to many sites ... (and) there is little reason to believe this situation will change in the near future," said the report.

As for protection of Russia's deadly pathogens, the GAO said after four years of effort, little progress has been made in addressing security at 49 Russian sites where the two countries have collaborative programs to improve safeguards.

It said the Defense Department, which leads that program, "has limited information on the location and security" of many of these sites where Russia continues to store deadly anthrax and pathogens that cause smallpox or the plague.

Earlier this month, a report by a group of Harvard University researchers said that only 37 percent of the potentially vulnerable nuclear material in the former Soviet Union is being adequately protected. The GAO produced a similar percentage.

At a news conference releasing the Harvard findings, Sen. Richard Lugar, R-Ind., chairman of the Senate Foreign Relations Committee, acknowledged the continuing problem of access to Russian facilities.

"Russia has got to be a partner," said Lugar, who 12 years ago was co-author along with then-Sen. Sam Nunn, D-Ga., of the law that authorized the beginning of the U.S. assistance program on nuclear materials.

Lugar cited a lengthy list of cases where Russians have rebuffed the United States in seeking access to nuclear sites, but said it would be "absurd" to abandon the program because of this.

"What alternative do we have?" asked Lugar.

The GAO report said that of the 600 metric tons of weapons-usable nuclear material in Russia, only about 228 metric tons is being kept at facilities with enhanced safeguards under the U.S. assistance program.

"Despite years of negotiations, Russia will not let (the Energy Department) visit or begin work at nearly three quarters of he buildings in the weapons complex," said the GAO.

Energy Secretary Spencer Abraham has outlined an expedited U.S.-Russia program, with increased U.S. access to sites under the 2001 agreement, with a goal of having all of Russia's nuclear material secure by 2008.

But the GAO said "with the department's lack of access to many of the most sensitive sites in Russia's nuclear weapons complex" it is unlikely that DOE will achieve the 2008 target.

The GAO said DOE has finished work at only 14 of 133 buildings in Russia's weapons complex. A bright spot, the GAO acknowledged, was progress in protecting nuclear material belonging to the Russian Navy where 85 of 110 buildings have had security improvements.