The United States will participate with Britain and Costa Rica in an international effort to negotiate a "regularized" flow of refugees from Cuba, it was announced here today.

But according to U.S. officials, there is no certainty that the Cuban government will talk to the international negotiating team and no date has yet been set for its visit to Havana.

The officials also made clear that whatever the outcome of negotiations, the task of receiving the majority of refugees will remain with the United States. There is hope, however, that the regularized flow, by air, could reduce the current rate at which Cubans are arriving by boat in Florida. More than 23,000 have landed in the last two weeks.

The U.S. decision to join the negotiating team came at the end of a two-day conference here that brought together representatives of 23 nations and five international organizations seeking to smooth the current chaotic exodus of refugees.

Well-informed sources said that the United States supported the conference effort to shift attention from the bilateral problem between Washington and Havana back to an international context that existed when the crisis began -- with the occupation of the Peruvian Embassy in Havana by 10,000 refugees last month.