The city cannot dismiss the company providing food service at the Washington Convention Center just because the firm is part of a conglomerate that has business ties to South Africa, the center's board learned yesterday.

However, firms seeking other contracts at the center will now be required to disclose whether they have any business dealings with South Africa.

"We will consider the moral question . . . along with other things," said board chairman Edward A. Singletary, who added that the center was unaware of the South Africa ties of the food service operator when the contract was awarded last year.

The issue arose when council member John Ray (D-At Large) urged Mayor Marion Barry to consider dismissing Sportservice Corp., a Buffalo-based firm that controls the contract, because a division of its parent company is part of a joint venture that holds the food service contract at Jan Smuts Airport in Johannesburg. Barry asked the convention center's board for advice on the matter, and the board sought an opinion from the center's general counsel, David W. Wilmot.

"Political and moral considerations aside, we have no sound legal basis for terminating the contract," Wilmot told the board. He said the city would risk serious legal penalties if it attempted to force out Sportservice because there was no requirement in the contract prohibiting South African business dealings.

Ray, in an interview after the meeting, criticized the board for not adopting a more hard-line policy against doing business with firms that have South African business ties. He added he believes that the South African issue and other questions raised about the food service contract illustrate that the board "was very sloppy" in awarding it.

Ray said the South African ties of Sportservice's parent company were described in the company's brochure. "I find it hard to believe that members of the board didn't look at the brochure," Ray said.

During yesterday's meeting, board member William Lucy, who is black, said he was refused service at a segregated restaurant at the Johannesburg airport several years ago before Sportservice's parent company became involved there. "It's something that sort of sticks in your memory," said Lucy, who is also secretary-treasury of the American Federation of State, County and Municipal Employees (AFSCME).

A spokesman for Sportservice's parent company, Delaware North Companies, Inc., has said that all of the company's restaurants, cafes and other facilities at the Johannesburg airport are integrated, which was a decisive factor behind the company's decision to begin operations there in 1981.

Lucy, who became a board member after the contract was awarded, said the center should ask Sportservice's parent company for a report on the company's operations at the Johannesburg airport as a precaution against any further possible embarrassment to the city.

The meeting was then closed to the public for about 15 minutes at the request of Wilmot, who said he wanted to discuss a "procedural question."

When the meeting was reopened, Singletary said the board would forward a brief response to Barry. An informed source said the staff will also pursue Lucy's suggestion and ask Sportservice for a report on its parent company's South African operations.

In a related action yesterday, a council committee chaired by Ray postponed a vote on a bill that would allow Sportservice and its partner to obtain a permanent license to dispense liquor at the new center after council members raised questions about the impact of the legislation.