The United States, breaking a silence, apparently has agreed to begin discussions toward raising new contributions for the International Development Association (IDA), the soft-loan affiliate of the World Bank.

World Bank Senior Vice President Moeen A. Qureshi said after a meeting of the deputies of IDA that the negotiations would probably begin in Paris in late January and had "unanimous" support. He said he expected them to be completed within a year.

The deputies conferred prior to the annual session of the boards of governors of the World Bank and International Monetary Fund, which begins here next week.

The Reagan administration previously had refused to commit itself on whether it would support raising new funds for IDA, which is financed by the industrial nations to make development loans to the world's poorest countries. Qureshi had said earlier that without U.S. support the program could end.

Currently, IDA is disbursing $9 billion in a three-year program that began in July 1984. About 93 percent of all outstanding loans are to countries with per capita incomes of less than $400 a year.

Qureshi said, however, that the deputies had considered hardening IDA's terms for lending money. It now lends for 50 years with no interest, though it charges an annual service fee.

Meanwhile, the issue of a general capital increase for the World Bank appears to have been set aside, at least temporarily. In remarks intended as background for his speech to the joint session of the IMF and bank on Tuesday, bank president A.W. Clausen said, "We're going ahead full throttle" for the next two years, even without a general capital increase.

Today's meeting of the IDA deputies appeared to break a logjam over the question of new funding for the association, which relies on direct contributions from 33 countries, most of them in the industrialized world.

The United States has pledged to contribute $750 million a year to the current program, down from the $1 billion that it put annually into previous lending programs.

IDA officials had been hoping that the United States would agree to renew its contribution for the coming loan program, the IDA's eighth, at least at the previous level. But there was concern that the White House would not go along.

Qureshi declined comment on the level at which new contributions might be made. He said tightened terms were being considered for "creditworthy" countries.

U.S. officials were not available for comment on Qureshi's remarks.

In his remarks, Clausen also said that "we are currently under no constraints" in making loans to client nations. The present pace of bank lending is around $13.5 billion a year, a level that the Group of 24 -- representing all the developing nations -- today urged be raised by a 6.2 percent real annual rate.

The Group of 24 said that the lending level should reach $20 billion by 1990, supported by "a substantial expansion" of the bank's capital base.

Earlier, Clausen had spoken in terms of a $40 billion minimum increase in the bank's capital, a demand he has withdrawn in the face of U.S. opposition. He indicated yesterday that even if the bank can continue to lend at around current levels for the next two years, a general capital increase will be needed later.

Clausen, pressed on reports that he would resign because of U.S. dissatisfaction with his leadership, said that he may have a statement on his future plans when the conference ends. He will hold a press conference Friday.