Senior officials from 12 countries concurred Saturday on the broad structure of a peace plan aimed at ending the Cambodian conflict but failed to come up with an agreement for endorsement by the warring factions.

"I cannot present a draft because the draft is still being developed," said Indonesian Foreign Minister Ali Alatas, co-chairman of the meeting."It is still far from complete," he said. "It is still very tentative."

Alatas told reporters he and co-chairman Claude Martin, director for Asian Affairs in the French Foreign Ministry, "have been requested to develop the substantive aspects and issues further."

For two days representatives of the five permanent members of the U.N. Security Council - the United States, the Soviet Union, China, Britain and France - met with delegates from the U.N. secretary-general, Australia, Canada, Japan, Laos, India and Malaysia in a bid to come up with a document to submit to the rival Cambodians for their approval.

There was no explanation why the session, originally scheduled for five days, ended suddenly.

Alatas reaffirmed his intention to meet with the members of the Cambodian Supreme National Council in Paris "to seek their understanding and support of the progress made so far."

He also expressed the hope of reconvening the International Conference on Cambodia, which broke down last year in a deadlock over a power-sharing agreement.

"I can say with pleasure the meeting made significant progress," Alatas insisted. "There was general concurrence among the participants on the structure and the approach upon which the prospective draft will be formulated."