The future of a controversial United Nations working group which deals with disappeared persons is worrying UN human rights officials after both the United States and Canada voted to cut its budget.
Although the funding cuts were voted down, officials and diplomats are worried that the Canadian and American votes could encourage critics of the group, lead by Argentina and the Soviet Union, to mount another attack when the group's mandate comes up for renewal Feb. 1.
Diplomatic observers here assume the US decision was in line with the policy of the Reagan administration to ease up human rights pressure on allies in Latin America.
In its first report last year, the human rights group disclosed between 12, 000 and 15,000 people had disappeared in 15 countries - 9,000 of them in Latin America. At their latest session here in December, the five members of the group are said to have reviewed almost 20,000 cases in 20 countries.
There are now said to be over 2,500 disappeared persons still unaccounted for in Argentina, and there are known to be 2,000 bodies buried throughout the country.
UN officials and diplomats here view the human rights ''missing persons'' group as vital in efforts to improve the effectivess of UN human rights machinery, which has been criticized for ''selectivity'' in singling out Israel, Chile, and South Africa for special investigation.
Last year the group intervened by cable on behalf of over 20 victims within 48 hours. ''If we've saved one life it was worth the money,'' said Mr. Theodor van Boven, Director of the Human Rights Division.
Despite this, several governments, led by Argentina, have reacted angrily to the zeal with which the group interviewed witnesses and the forthright presentation of this year's report which concluded that over half the disappearances had occurred in Argentina. It also gave details of 16 clandestine centers where it said detainees had been held between 1976 and 1979 and tortured.
Last year's commission extended the life of the group, and an equally controversial probe into human rights in Chile, for one more year until the 1982 session.
But the UN's advisory committee on administrative and budgetary questions, which met recently in New York to review the UN budget, decided that the specially-allocated funds for the ''missing persons'' group, totalling $54,900, should be cut by about $33,000, and the money found from the regular budget of the UN human rights secretariat.
When the proposal came before the fifth committee of the General Assembly for rubberstamping, it was overturned in a 29 to 24 vote on a motion by Denmark. Of the Western countries, only Canada, the US, and Turkey voted to discontinue funds.
Meanwhile, the UN working group's second report, is due out shortly. Guatemala, El Salvador, Ethiopia, Uganda, and Iran are said to be among the new countries investigated.
Ironically, one country where disappearances have stopped is Argentina. In 1980 there were 85 new cases reported and 1981 only 8, of which 7 were later accounted for.