Likening the current Indochinese refugee crisis to Germany's explusion of Jews in the 1930s, a congressional subcommittee yesterday called for an immediate emergency session of the U.N. General Assembly to deal with the problem.

At a hearing of the House Foreign Affairs sub-committee on Asia and the Pacific, subcommittee chairman Lester L. Wolff (D-N.Y). called the present situation "a disaster which . . .threatens to explode in death for perhaps 500,000 men, women and children."

Assistant Secretary of State for Pacific Affairs Richard C. Holbrooke, who testified before the subcommittee, said he agreed with the German analogy, and squarely placed the blame for the crisis on the Hanoi regime.

"The Vietnamese government has embarked on a deliberate effort to rid itself of those elements of society which it considers undesirable," Holbrooke said in a prepared statement.

Holbrooke told hte committee that in 1978 the average monthly number of Indochinese who reached safe havens after fleeing their homelands by boat was 7,500. During the first quarter of 1979 that average rose to 11,000 a month, he said.

In April, according to Holbrooke, 34,000 "boat people" reached temporary asylum, in Southeast Asia and in May the figure rose to 54,912. These figures do not include, Holbrooke said, scores of thousands of Cambodians and Laotians who have fled to Thailand, large numbers of refugees who are believed to have fled to China, or between 30 and 60 percent of the boat people who are believed to have died in their efforts to escape Vietnam.

There are now 330,000 Indochinese in Thailand, Malaysia, Indonesia, Hong Kong, Singapore and the Philippines, waiting for permanent resettlement in the West, according to the State Department. By September that number is expected to reach more than half a million. But Thailand, the major recipient of refugees thus far, has refused to let any more boat people land, and has reportedly begun forcing some 80,000 Cambodian refugees back across te border.

Malaysia and Indonesia both announced this week that they would not accept any more refugees. If they hold to this position, refugees fleeing the communist countries of Indochina will have virtually no place to go.

Vietnam has reportedly made clear its intention to force out as many as 1.2 million ethnic Chinese who are considered by the Hanoi regime a dangerous "fifth column" sympathetic to its enemies in Peking, according to State Department officials.

Holbrooke, who was in China last week, said the Peking government informed him it had accepted 230,000 Vietnamese-Chinese refugees so far, amounting to about 10,000 a month during the last five months. But he said there is no independent confirmation of these numbers, and some of the refugees may be sent to Hong Kong.

Holbrooke strongly criticized Vietnam for its incursion into Cambodia, the source of many new refugees, and the related risk that the war there will spill into Thailand. Holbrooke deplored, as well, the increasing Soviet presence in Vietnam.

The refugee crisis remains the most pressing concern, however. Secretary of State Cyrus Vance announced at a news conference yesterday that it will be discussed with the Soviet Union at this weekend's Vienna summit. British Prime Minister Margaret Thatcher has called for an international conference on the issue.

"Thirty thousand refugees may have died already in the month of May," said one State Department official after the hearing. "Only 10,000 refugees are being resettled by all the permanent asylum countries such month." (The United States takes 7,000).

"That means that each month about three days worth of arrivals in the first asylum countries are being taken off their hands," the official said. "Right now the situation is beyond the grasp of the international community to cope." CAPTION: Picture, Assistant Secretary of State Holbrooke, right, with Rep. Wolff before testifying. By James K. W. Atherton - The Washington Post