National Security Affairs Adviser Zbigniew Brzezinski and the National Security Council are reviewing a request by the State Department to approve emergency admission of 15,000 Indochinese refugees stranded in temporary camps and escape boats throughout Southeast Asia, a White House spokesman said yesterday.

Calling the request "an effort to make a significant gesture" in relieving the plight of the refugees, a State Department official said that, if granted, it would give emergency authority to the Attorney General to admit the refugees. The measure would bring the number of Indochinese refugees admitted since the fall of Saigon in 1975 to 160,000.

While the White House has been described as sympathetic to the measure, and Secretary of State Cyrus R. Vance in a speech last week urged international consideration of the refugees' plight, some members of Congress are thought to be unenthusiastic about the prospect of further large-scale admission of Indochinese into the United States.

Under current law, 100 Indochinese have been admitted to the United States each month for the past six months; the number will be increased to 300 per month for the next three months.

Attorney General Griffin B. Bell has the legal authority to admit the additional 15,000 refugees, but traditionally key members of Congress are consulted before such decisions are made.

Budgetary considerations and congressional opposition to further admission of immigrants from Southeast Asia could slow down or prevent approval of the emergency appeal. The cost would be approximately $1,000 per refugees plus travel costs and a relocation grant, according to officials.

More than 80,000 Indochinese refugees are living in poverty in camps in Thailand or on boats offshore. An additional 4,500 or more boat-dwelling refugees are scattered throughout Malaysia, most of them unable to find even temporary haven in Asian countries, according to State Department officials.

Refguees are currently able to enter only some Western European countries and Australia.