Declaring that the District of Columbia City Council improperly hired 33 workers under a federally financed jobs program, the U.S. Department of Labor has ordered the city to pay their salaries back to the U.S. Treasury.

Nine of the 33 workers who are still on the payroll of the council's CETA program must be terminated immediately, Assistant Secretary of Labor Ernest G. Green told Mayor Walter E. Washington in a letter released yesterday.

The mayor's office said it had no estimate of what the city would owe, but one educated guess put the figure in excess of $250,000. No effort would be made to collect the money from the affected employes, officials said.

Green also warned the city not to put any more people into CETA-financed jobs "which may be subject to political activity."

CETA, the Comprehensive Employment and Training Act, was enacted by Congress during the recession of the mid-1970s chiefly to provide jobs for the hard-core unemployed. Part of the program also was targeted to employ recent college graduates unable to obtain professional work.

Its enactment coincided with the advent of home rule in the District, and the city used CETA to pay salaries of the council's much-expanded staff. About 40 of its 130 employes are paid with CETA funds.

Following a two-month investigation last spring, the Labor Department asserted that several council members or their staff aides had violated CETA rules by asking that certain individuals be hired by name. The rules provide for hiring from among applicants certified by D.C. manpower officials without prior selection by council members.

With his new letter, Green listed 28 instances of specific name requests. Of these, only eight are still on the payroll. The ninth worker that Green said should be terminated was found to be ineligible for CETA employment for another unstated reason.

Of the 28 on Green's list, one former worker -- Absalom Jordan Jr. -- had been terminated earlier after a finding that he had engaged in personal political activity while a CETA employe. An associate of council member Douglas E. Moore (D-At Large), Jordan unsuccessfully sought the Democratic nomination in the September primary to succeed Moore.

Green's letter did not raise questions about the hiring of two other CETA workers whose names had been widely publicized when the original Labor Department report of its investigation was issued last July.

They were Lorethea Davis, the wife of an affluent dentist who was an official in the unsuccessful mayoral campaign organization of Council Chairman Sterling Tucker, and Alan Winter, son of council member Nadine P. Winter (D-Ward 6). Both were later shifted off the CETA rolls onto the basic council payroll.

Green's letter was the latest in an exchange between Labor Department and District of Columbia officials over the issue. It was written at a time when the national CETA program is under fire in the Office of Management and Budget.

OMB, preparing the proposed presidential budget for the 1980 fiscal year, has recommended that CETA spending be cut to $8.2 billion from the $10.8 billion appropriated for 1979. The Labor Department has asked for an increase to $12.5 billion.

One OMB target would be the public service jobs program, under which the D.C. Council employes were hired. Other cuts would come in summer youth jobs and in youth job training.

The Labor Department and a coalition of city, organized labor and black groups are appealing to President Carter to support at least part of the increased funding.

The reaction at the District Building was muted after the existence of the letter became known.

Mayor Washington issued no statement, and both he and Tucker ordered city lawyers to meet and prepare a response for Green. In his letter, Green said the city is entitled to a formal hearing before a final order to pay back the CETA payroll funds is issued. It seemed likely the city would seek such a hearing.

Some of those whose jobs would be terminated were stunned by the Green letter.

"I didn't do anything improper (to get a job), and I'm caught in the middle," said Ann Meister, an attorney on the staff of the council's judiciary committee.

When interviewed for her job by a staff member, Meister said, she was told she had to be certified for CETA, which she did. The committee then asked that she be hired.

Meister said she did not meet the committee chairman, David A. Clarke (D-Ward 1), until several weeks after she went onto the payroll.

"I don't think it's very fair," was all that LaVerne White, secretary to the staff of the council's transportation committee, would say.

Anne Snodgrass, committee staff director, said White was doing volunteer work for the committee when the CETA job became available, so the committee asked that she be hired. White had been previously certified as eligible for CETA, Snodgrass said.

Others still on the payroll, affected by the Green directive, are Deirdre Daly, Adam E. Maier, Earlene Mathews, James O. Thompson, Nancy E. Valencia and Anthony Cooper. Cooper was the one Green described as ineligible for the CETA job.