An unexpected surge in the numbers of refugees coming out of Indochina and Eastern Europe, combined with sometimes erratic U.S. government policies toward them, has pushed many of the voluntary agencies responsible for their resettlement in the United States to the brink of financial disaster.

According to spokesmen for these agencies and sources in the State Department, the government has failed to pay some $7 million promised for the care and maintenance of the refugees in Europe and their resettlement in the United States.

Gaynor Jacobson of Hias, the largest of the agencies concerned primarily with European refugees, said yesterday that if a solution is not found soon, as many as 10,000 people, mostly Soviet Jews, could be stranded in temporary Austrian and Italian quarters with no means of coming to the United States.

At the same time, however, John E. m/cCarthy, executive director for Migration and Refugee Services of the U.S. Catholic Conference, has written to he president to assure him that the conference is ablt to accept and resettle 7,000 Indochinese refugees immediately.

At a press conference yesterday, he said his organization could handle as many as 84,000 Indochinese resettlement cases a year if necessary to relive the plight of people such as the 5,000 refugees now stranded on ships near Hong Kong and Manila and the 150,000 in meager temporary camps scattered around noncommunist Southeast Asian countries.

McCarthy appealed to the president to take immediate action to relieve these refugees' suffering by assuring the governments of the Philippines, Hong Kong, Thailand and Malaysia that the United States can, and is willing to resettle them.

McCarthy said that the government funding for the resettlement of the Indochinese has been adequate so far though the $350 per person that it supplies to the voluntary agencies has to be considerably augmented by te agencies' own resources and the smaller resettlement organizations may suffer as a result.

The contrast in the allocation of resources and the ability to cope with the two separate refugee groups results from unforeseen events, government miscalculations, the differing needs of the two groups, and a national policy toward refugees generally that has yet to be clearly defined by legislation, according to government and voluntary agency sources familiar with the situation.

According to a November memo from Secretary of State Cyrus Vance, the current flood of Indochinese refugees began over a year ago when the number reaching the shores of noncommunist Asian countries jumped from 500 to 1,500 a month.

Eight months ago the rate had increased to 5,000 and by October it was exceeding 12,000 a month.

The situation eventually reached crisis proportions as Malaysia and other countries refused the refugees permission to land and sent them back out to sea in leaky boats. The State Department did get a supplementary appropriation to help fund the resettlement of some 50,000 Indochinese refugees who are expected in this country by May 1.

By contrast, the increase in the number of Eastern European refugees came suddenly over the last few months of last year.

Before August, according to Jacobson, there were about 1,700 to 1,800 a month, the vast majority of them Soviet Jew. Then the surge began and in December alone, 4,200 refugees were allowed out of the Soviet Union.

Of these, about 55 percent are destined for the United States, Jacobson said.

Hias had started running our of government money for resettlement as early as May, because of the declining value of the dollar abroad and inflation in the United States. Other voluntary agencies such as the Tolstoy Foundation and the International Rescue Committee Began feeling the same crunch.

"We looked at the situation back in June," one State Department official said yesterday, "but it did not seem as compelling as the Indochinese problem and was not acted on by the administration."

When the flow of European refugees suddenly increased, the State Department told the voluntary agencies to keep supplying their services, Congress would be asked for more money and they would be reimbursed, according to several sources.

State Department sources said yesterday that they would use some of the money in their Refugee Emergency Fund to try to help the voluntary agencies, but there is only $3 million left in it. Earlier this year, $5 million was withdrawn for the Indochinese resettlement.

For request for funds to help European refugees came so late in the year that Sen. Daniel K. Inouye (D-Hawaii) of the appropriations subcommittee on foreign operations would have had to change the budget cycle to accommodate it. He declined to do that.

"That Congress is greatly concerned about the organization and management of our overall effort," he wrote to Vance last month. "In my opinion, resolution of these overall problems is going to be necessary if we are to establish a rational and coherent refugee policy."