A D.C. foreign currency trading office remained closed yesterday as five prominent antiapartheid demonstrators continued a sit-in at the firm's K Street offices to protest the sale of South African gold coins.

The peaceful demonstration at Deak-Perera Inc. began Monday when the protesters, led by Randall Robinson, executive director of TransAfrica, and D.C. Del. Walter E. Fauntroy, entered the establishment and vowed to stay "indefinitely" as a protest of the sale of Krugerrands.

The firm closed its offices at 1800 K St. NW early and the protesters camped out in the lobby overnight, sleeping on sheets of newspaper spread on the bare stone floors.

A Deak-Perera spokesman who asked not to be identified expressed concern that the demonstration could possibly continue for several more days. "I don't know when we're going to reopen," said the spokesman.

Barney Zeng, office manager, said, "We won't have them arrested, but we won't stay closed forever, either."

The protesters, who brought portable toilets as well as fruits and juices, would not say how long they planned to stay. A security guard was stationed in the lobby overnight, and in the morning, Deak-Perera employes gave the protesters doughnuts and coffee as a "friendly gesture," Zeng said.

"It was a way of making it a more human situation between them and us since we are confined in this small space," about the size of a coffee shop, Zeng said.

"We have nine employes here. We represent one point of view, and they're representing another. But as long as they're here, we have to coexist," he added.

Zeng said that while several prospective customers were turned away when they arrived at the office, "we make arrangements on the telephone. We refer our customers to other institutions such as banks where they can make purchases. At this point, the protest is not a big problem."

Robinson said the aim of the protest is to enlighten the public to what he called the "abhorrent" ramifications of Krugerrands.

"We feel refreshed, and we're fit for staying as long as it takes to educate the American people about the connection between their purchases of Krugerrands here and the racial oppression of 22 million blacks in South Africa," he said.

Robinson and Fauntroy, who serve as cochairmen of the Free South Africa Movement, were joined by three members of the movement's steering committee: Mary Frances Berry, a U.S. Civil Rights commissioner; Sylvia Hill, associate professor of criminal justice at the University of the District of Columbia, and Roger Wilkins, a member of the Institute for Policy Studies.

On Thanksgiving eve, Robinson, Fauntroy and Berry launched what has become almost daily demonstrations at the South African Embassy at 3051 Massachusetts Ave. NW. The demonstrations, which have resulted in more than 2,000 arrests since they began, including two more yesterday, are seen as helping to raise public concern about apartheid.

A D.C. police officer monitoring the Deak-Perera sit-in said, "We can't arrest anybody until the owners make a complaint. I don't think they want the hassle of fighting these people in court."

David Scott, a spokesman for TransAfrica, said, "We have received no response yet from Deak-Perera, but I've heard that they intend to try and wait us out . . . . It's a waiting game."