Malaysia has turned back 13,000 "boat people" since it adopted a tougher policy toward Vietnamese refugees a week ago, a high government official said yesterday.

This brings to 55,000 the number of Vietnamese Malaysia has forced back out to sea since Jan. 1, according to Kassim Ahmad, the parliamentary secretary to the Foreign Ministry. News agencies said Kassim made his remarks in response to questions made in Malaysia's parliament.

Meanwhile, Thailand said it would temporarily halt its forced repatriation of refugees from Cambodia. Prime Minister Kriangsak Chamanan said Thailand would await the outcome of a proposed U. N-sponsored conference on the refugee crisis currently overwhelming the countries of Southeast Asia.

Thailand's decision to compel 45,000 Cambodian refugees to return to their country and Malaysia's announcement ten days ago that it would force some 76,000 Vietnamese refugees on its shores back into their fragile boats has propelled the long-smouldering Indochinese refugee into the world's consciousness.

In recent months there has been an explosive increase in the number of refugees fleeing the CoCommunist states of Indochina. An estimated 55,000 fled in May. This is more than five times the number the so-called asylum countries, such as the United States, Australia and Canada, are prepared to accept each month.

The refugee question has fored its way into the agenda of President Carter's current talks with Japanese officials. It is to be raised at the economic summit of seven industrialized countries later this week in Tokyo. The U.S. delegation at the Vienna summit meeting on the SALT II treaty earlier this month brought it up in their talks with their Soviet counterparts.

Most attention has focused on a British proposal for an international conference on the problem.

U.N. Secretary General Kurt Waldheim told a group of congressmen in Washington yesterday that a conference on rerugees in Southeast Asia will be held in Geneva next month. Rep. Lester Wolff(D.-N.Y) said 52 nations have been notified of the meeting, which will be held some time in the week of July 13.

The nations of Southeast Asia have been bitter at what they say is the world community's failure to assist them in dealing with the flood of refugees. They have also been trying to pressure the Vietnamese government into halting the flow.

An Indonesian official indicated yesterday, however, that Hanoi itself is taking a tough line on the question. The official, Foreign Minister Mochtar Kusumaatmadja, indicated that talks with a special Vietnamese mission to Jakarta are near collapse.