World Bank President A. W. (Tom) Clausen said tonight that a group of European nations and Japan had made "considerable progress" in covering a $1.5 billion shortfall in this year's funding of concessional aid to poor countries through the International Development Association, the bank's soft-loan agency.

The shortfall was triggered by the failure of the United States to meet its original schedule of IDA contributions, a failure that has created widespread bitterness on the part of the poor nations toward the United States.

But Clausen admitted, following a two-day meeting of the joint World Bank-International Monetary Fund development committee, that there was bound to be some remaining gap in the program, originally set at $12 billion for the three years ending in fiscal 1983, "unless Congress changes its position, and I don't expect that to happen."

And although Clausen urged that discussions begin immediately on the next IDA program, starting in 1984, he was equally candid in saying that "I wouldn't bet very much money" that it would be adequately funded "because of the budget restraints of the major donor." How much, if any, money Congress will appropriate for IDA in fiscal 1983 is an open question.

The development committee wound up a week of international financial meetings here, including a session of the IMF interim committee, which Thursday urged member nations to maintain a tight monetary stance until inflation is defeated.

The IDA program is in trouble, because the United States, which contributes about 25 percent of IDA funds, cut its fiscal 1982 contribution from an expected $1 billion to $700 million. Since other nations contribute on a pro rata share, a deficit of about $1.5 billion has arisen for IDA this year.

Clausen said yesterday that in one way or another, about $500 million of that $1.5 billion has been covered by other nations, including the Nordic group, the Netherlands, Japan and England. Those countries either agreed to give more than they had to on a pro rata basis, or agreed to concessional co-financing arrangements with IDA.

Yet another proposal welcomed by Clausen--as a second preference--derives from a French initiative to create a special, restricted loan fund for poor nations, which could not be used to finance purchases from the United States.

The development committee communique painted the prospects of the poorest developing countries as "particularly bleak, as they face stagnation, in some cases retrogression, in the period ahead."

Peruvian Prime Minister and Minister of Economy Manuel Ulloa Elias, selected yesterday as chairman of the committee, said that, despite the budget deficit problems that the rich nations had been talking about, they had to find ways of improving the flow of resources to the poor.The committee noted that the World Bank's energy loans now take up 25 percent of the total.