Deak-Perera, a foreign exchange and precious metals firm that sells South African krugerrands, closed its doors here yesterday afternoon after five demonstrators entered its offices and vowed to stay "indefinitely" as a protest against apartheid.

The Free South Africa Movement protesters, led by Randall Robinson, executive director of TransAfrica, and D.C. Del. Walter E. Fauntroy, entered the firm at about 12:30 p.m., a TransAfrica spokeswoman said, and stood in the front window holding placards that said: "Ban the Krugerrands."

Employes of the firm refused to file a complaint against the protesters, police said, and at 5 p.m., Deak-Perera's regular closing time, employes left the office at 1800 K St. NW. The protesters stayed behind locked doors and under the watchful eye of a building guard.

The protesters, who brought portable toilets and food to last a couple of days, would not say how long they planned to stay.

Robinson and other protesters demonstrated at the same Deak-Perera office in February. Deak-Perera officials refused to file a complaint, and there were no arrests. At the time, Robinson said he would return.

Meanwhile, weekday protests continued at the South African Embassy here, with 22 people arrested yesterday. The U.S. attorney's office has dropped charges against those arrested at the embassy, but a spokesman said it would prosecute anyone who is arrested a second time.

Protesters, Robinson said, are seeking an end to a U.S. policy that aims to bring about reform in South Africa through constructive engagement with its government. A day in court, he said, would give them a chance to make a public record of their charges of racial segregation practiced in South Africa.

Joining Robinson and Fauntroy, co-chairman of the movement, yesterday were Mary Frances Berry, Sylvia Hill and Roger Wilkins, members of the steering committee.

Shortly after the protesters arrived at Deak-Perera, a spokeswoman for the firm said, "We closed our offices because we don't want any problems." Demonstrators maintained that they did not disrupt the offices or attempt to interfere with customers.

As they stood in the firm's display window, smiling and holding large placards, the five protesters waved at passers-by.

Three people were arrested at a similar demonstration yesterday at a Deak-Perera office in Boston, police there reported.

Robinson, in an interview with a reporter via a walkie-talkie outside the Washington Deak-Perera office, said the firm "is one of the major distributors of krugerrands in the United States."

"This protest is to provide national attention to and to educate the American people about the enormous revenues South Africa gains through the sale of the krugerrands," he said.

Deak-Perera employes posted a sign on the front door announcing that the office was temporarily closed, saying, "We apologize for the inconvenience."

"Is there anyplace else to buy some foreign currency?" Stuart Sessions, 36, asked an employe through a thin gap between the glass doors.

"No, the banks are closed now. Try again tomorrow," the employe answered from behind the doors.

"I need some British pounds," Sessions told a reporter. "I plan to be vacationing there in a week."

He said he sympathized with the protesters. "This protest, I think it's probably reasonable. It should increase the pressure on the South African government," he said.