A D.C. Superior Court judge dismissed criminal trespassing charges against D.C. Del. Walter E. Fauntroy and three other prominent apartheid protesters yesterday, averting what would have been the first trial in the District against persons protesting South African racial policies.

However, a prosecutor said the government would file new charges against the four Free South Africa Movement leaders who were arrested May 12 at the downtown offices of Shell Oil Co. during a protest of the firm's investments in South Africa.

In a courtroom packed with Free South Africa supporters, Judge Frank Schwelb said he had no choice but to drop the unlawful entry charges after prosecutor Heidi Pasichow said she was not prepared to go to trial, which was set to begin yesterday.

Schwelb told the parties he was dismissing the charges "without prejudice" and the government was free to bring new charges -- a step Pasichow said the government would take.

The four demonstrators later criticized the government's unwillingness to go to trial yesterday and accused the U.S. attorney's office of trying to prevent an airing of their grievances and stifle publicity that would have come out of a trial at a crucial time.

The U.S. Senate, they said, is scheduled to begin debate soon on economic sanctions against racially segregated South Africa. Prosecutors "wanted to suspend the trial process during the Senate debate," said former U.S. civil rights commissioner Mary Berry, who was arrested along with Fauntroy, TransAfrica Director Randall Robinson and Sylvia Hill, a college professor.

Clendon Lee, a spokesman for the U.S. attorney, said his office would have no comment on the protesters' statements.