More than a dozen witnesses, all denouncing apartheid in South Africa, urged the D.C. City Council last night to approve a bill that would require the city to withdraw its investments from companies that operate in that country.

"Divestiture would not be just symbolic, but a concrete blow," said the Rev. Joseph Lowery, president of the Atlanta-based Southern Christian Leadership Conference.

The bill would require the city's retirement board to shift about $63.5 million of its $331.7 million in investments from such companies as Bechtel, IBM, Mobil, Coca-Cola and U.S. Steel, according to council member John Ray (D-At Large), author of the measure.

In addition, the city would have to remove about $4.2 million from checking accounts at American Security and Riggs National banks, Ray said.

Several witnesses and council members dismissed a warning on Wednesday from Rep. Stanford E. Parris (R-Va.) that if the measure passed he would oppose it in Congress.

"I know it will be difficult for this council to consider this issue," said Council Chairman David A. Clarke, "but it seems the kind of issue we ought to carry forward anyway."

Among those testifying last night was Dumisani Khumalo, an exiled South African journalist and a member of the New York-based American Committee on Africa, who opposes his country's policies. Khumalo said American corporations in South Africa maintain apartheid even though the companies contend they give jobs to some blacks who would be hurt economically by their withdrawal.

"If corporations were in the business of liking black people," Khumalo said, "they would start liking us right here in this country. They are in the business of profit." He said blacks in South Africa pay about $1 billion in taxes, but are still subject to repressive laws restricting human rights.

The hearing is scheduled to continue at 10 a.m. today.