Boston University's librarians and clerical workers yesterday ended their 11-day-old strike, and one hour later the university administration announced it would begin contract negotiations with their unions.

Spokesmen for the unions and for the university yesterday declined to say whether the actions were the result of a pre-arranged agreement.

Stephen Wagner, associate director of public relations at B.U., said yesterday the university has not officially recognized the unions and negotiations will be voided if the appeals courts withdraw certification of the unions.

Last December, the National Labor Relations Board certified District 65, which represents 900 clerks, typists, and technical employees, and Local 925, which represents 20 professional librarians.

The university appealed that decision and until yesterday refused to negotiate with the unions until the appeal process, which could take two years, is exhausted.

The clerical workers struck to force the university to recognize their union and begin contract negotiations. District 65 won a "tremendous victory" yesterday, Kathy M. Kautzer, a spokesman for the union, said yesterday.

"This is the first successful strike by clerical workers at any university in the country," Kautzer said, adding "There is no possibility the courts will overturn certification of our unions."

Contract negotiations could begin next week, she said.

"We're extremely pleased to have all our employees back to work." Wagner said yesterday. "It will be great to have B.U. back to a full-scale operation," he added.

A spokesman for the faculty union, which won a three-year contract last week after a nine-day strike, said all professors will resume teaching in their regular classrooms.

Until yesterday about 150 professors had classes off-campus to avoid crossing picket lines set up by the clerical workers, who had supported the faculty in its strike.