The tuition-free YWCA-operated day care center in Central Square closed yesterday because of financial problems and conflicts with the YWCA director.

The day-care center, open only to children of parents receiving welfare, had been operating on emergency funds provided by Gov. Michael S. Dukakis, Carol C. Davis, day-care center director, said yesterday.

The emergency funding ends today.

Edward T. Donovan, director of purchasing at the Department of Public Welfare, said yesterday that though the emergency funds are no longer available, other public welfare money is.

"We submitted legislation early in the year and we had every indication that it would be passed by now," he said. The legislation has not been passed yet, "but we still have funds. The center can keep going with absolute assurance of being paid," he added.

Davis said the YWCA director would have to go into Boston every week and pick up a letter from the Department of Public Welfare for the center to receive state aid now. The YWCA director refuses to get the letters, she said.

Margaret E. Sullivan, the YWCA director, refused to comment yesterday.

Davis said that much of the director's decision to close the center is related to a demonstration held by the Committee to Save Day Care on Thursday.

Grace M. Levin, a day-care worker at the Children's Community Day Care in Cambridge, said yesterday a group of 25 staged a sit-in at Sullivan's office to protest the center's closing. Sullivan refused to meet with the demonstrators.

Donovan called the decision to discontinue the center "unbelievable."

"They have a good program and we'd like to see it continue," Donovan said. "This agency is the only one of 80 in the same situation to close," he added.

Davis said parents of children in the center must find their own private baby-sitters or place their children on waiting lists for other centers.

"We have a feeling a lot of mothers will have to quit their jobs because of this," Davis added.