Negotiations between the Metro transit authority and the transit workers' union have recessed temporarily without reaching an agreement on a new labor contract, officials said yesterday.

The union's three-year contract with Metro expired yesterday, but Metro and union officials said the old contract's provisions will remain in effect until a new accord is signed. No strike or other disruption in transit service is currently expected, officials said.

Walkouts by Metro employes are prohibited by federal laws and contract provisions. Nevertheless, wildcat strikes have freqently occurred, including a a seven-day walkout in 1978. Local 689 of the Amalgamated Transit Union represents nearly 5,500 bus drivers, subway motormen, mechanics and other employes.

The negotiations appeared to have made headway on some issues and to have narrowed the number of areas under discussion, officials said. They noted, however, that substantial disagreements remain over key issues, such as wages and the union's controversial cost-of-living adjustment clause. The provision links wages with changes in the Consumer Price Index.

The recess in the talks was designed, officials said, to allow time for further study of last week's proposals and review by Metro's board of directors and union members. The recess may last for about 10 days, officials said.

The union and Metro both have the right to submit their disagreements to an arbitration panel by declaring an impasse in the negotiations. Union leaders previously indicated that such a move was likely, but they did not call for arbitration last week. Metro officials expressed hope that a new contract could be negotiated without arbitration.