D.C. City Council Chairman David Clarke said yesterday that the council will provide enough additional funds to allow the University of the District of Columbia to absorb Antioch Law School, a move that the UDC board backed late Thursday night.

However, Clarke said the university will have to provide a clear plan of how it intends the school to operate.

Last week, the council approved $1.3 million for the takeover as part of its budget for fiscal 1987, which begins Oct. 1. Accountants for the university said about $700,000 more would be needed for UDC to acquire the innovative 14-year-old law school, which has been threatened by financial and accreditation problems.

The resolution favoring a takeover, passed by the trustees on a 10-to-2 vote, did not specify details of the transfer. Board members said yesterday that several issues, including assurances that Antioch would retain its accreditation, must be resolved before UDC would acquire the school.

"All we said was, 'I intend to buy your house.' It was not the final deal," said Trustee Herbert O. Reid, who was named head of a committee to plan the transfer. "We're still at the stage where Antioch is selling their house. That's different than talking to the building inspector who says it might cave in.

"I'm very worried that we don't take over a law school that's disaccredited tomorrow," Reid said. "Just because it changes ownership doesn't mean it can stay accredited if it keeps running the same way."

American Bar Association evaluators have recommended withdrawing Antioch's accreditation, citing deficiencies in facilities, finances and academic standards. But the ABA has postponed final action, and Antioch officials have expressed confidence that an infusion of funds from UDC will be enough to solve those problems.

Yesterday, law school dean Thomas J. Mack said that the budget he proposed is designed to meet ABA concerns.

"I don't think you can ever get formal assurances from the ABA," Mack said. "But I'm sure that informally we can get any assurances that we need if we seek them out."

Clarke praised Antioch yesterday, but said UDC must provide details on tuition rates, any changes in academic programs and steps being taken to increase the number of District residents attending the school, before the council will provide any funds.

He said he hoped the plan will be ready by mid-April. This would permit the council to include additional funds in its supplemental budget for the current fiscal year, allowing UDC to take over the law school on July 1.

About 35 of the law school's 362 students are District residents, but Clarke said D.C. students should soon become a majority at the school.

"That's our hope, too," Mack said. "But it can't just be done next fall."

Under the tentative budget presented by Mack to the UDC board, nonresidents would continue to pay Antioch's current tuition of $7,250 a year, but tuition for D.C. residents would be $3,600.

Several UDC board members said they feared that many nonresident students would claim D.C. residence since the university now only requires 90 days in the city to do so. Mack said if the waiting period was raised to a year, the number switching would be small.