A bill designed to make it more difficult for firms with business ties to South Africa to obtain city contracts received strong backing yesterday during a hearing before a D.C. City Council committee.

Jacqueline M. Wilson, a representative for the Washington Office on Africa, a national group that advocates majority rule in South Africa, told the Government Operations Committee that the measure would put economic pressure on local firms doing business in South Africa to reconsider their policies.

"For the white business community in South Africa, apartheid has now become financially imprudent, changing them into active opponents of apartheid," said Wilson, one of seven witnesses who supported the bill. "We must work to have U.S. corporations assume the same position."

The bill, introduced by City Council member John Ray (D-At Large), would require businesses bidding for D.C. government contracts to submit sworn affidavits stating whether they do business in South Africa or Namibia. Any company that does business in South Africa would be assigned demerits, based on a formula to be devised by the mayor.

The demerits would lessen a firm's chances of being selected, and in some cases the city would be forced to pay more for goods and services under the proposed legislation. For example, if three companies bid for a contract and the highest bidder was the only firm that did not have ties to South Africa, that firm might be awarded the contract.

A District law that went into effect last year prohibits the city from investing its funds in banks and institutions that do business with South Africa. Ray, who also proposed that law, said the new proposal is another step toward having the city sever economic ties with South Africa's apartheid regime.

William B. Johnson, director of the D.C. Department of Administrative Services, the city's chief purchasing agency, noted that a plan to assign demerits might, in some cases, conflict with the requirements attached to federal grant money used for city purchases. Johnson recommended that such purchases be exempted from the proposed demerit system.

Earlier this year, the Maryland-National Capital Park and Planning Commission adopted a strict policy barring any transactions with firms that have business ties to South Africa. The planning commission oversees zoning matters and recreation facilities for Montgomery and Prince George's counties.

Ray said he ruled out seeking similar regulations for the District because the city may have to make exceptions if all the firms bidding on a contract have South African ties.