German Finance Minister Theo Waigel, seeking to reassure U.S. officials that his government will fulfill its pledge to help pay for the Persian Gulf War, told President Bush yesterday that Germany will complete its promised 1991 payment of $5.5 billion on Thursday.

Waigel's visit here this week was prompted by suggestions from opposition Social Democrats in Germany that the Bonn government reconsider the size of its commitment in view of the brevity of the U.S.-led victory over Iraq.

Several members of Congress had resented the implication in Germany that the United States was seeking to make a profit by asking allies to contribute more than the war had cost. The incident threatened to aggravate American attitudes toward Germany, already irritated by German peace demonstrations against the U.S. bombing of Baghdad, by Bonn's refusal to join the military coalition arrayed against Iraq and by revelations that German firms had helped Iraq amass stocks of poison gas and other weapons of mass destruction.

While the German government did not send forces to the gulf, arguing that its constitution barred its troops from fighting outside NATO territory, it contributed $1.07 billion last year toward defraying war costs and pledged an additional $11 billion this year: $5.5 billion to defray the expenses of U.S. forces and the balance to other countries that have suffered financial reverses because of the gulf crisis. Bonn paid the United States $2.16 billion on Feb. 20 and $1.66 billion on March 15. Waigel said that the final $1.68 billion would be paid Thursday.

Bush, who appeared briefly with Waigel, praised the German contribution and challenged estimates released Monday by the Congressional Budget Office that the cost of the war will be about $40 billion, far less than the $54.5 billion pledged by U.S. allies. "I'm afraid it's not going to be any cheaper . . . than original estimates," he said.

White House spokesman Marlin Fitzwater insisted that ultimately the cost of the war is "going to be higher than the amounts that are pledged {by the allies} -- there's no question about that." He said the difference would be a "considerable amount."

Fitzwater also praised the contribution of Japan, another country criticized for what has been perceived as grudging support of the war. In January, Japan pledged 1.17 trillion yen, which was worth $9 billion at the time. Since then, the yen has weakened against the dollar, reducing the value of the pledge to $8.6 billion, and Japanese Prime Minister Toshiki Kaifu said this week his country would not make up the difference.

A tally released yesterday by the Defense Department said cash and in-kind contributions so far from more than six countries that have made commitments to help defray the costs of the war total nearly $23 billion. This includes $7 billion from Kuwait, $6.9 billion from Saudi Arabia, $4.7 billion from Germany, $2 billion from the United Arab Emirates, $1.5 billion from Japan, $78 million from South Korea and $3 million from others. An additional $5.7 billion from Japan is being processed.

Waigel's visit here had initially evoked some hostility because of suggestions that he was coming, as one congressional source put it, "to look at the books to ensure that Bonn wasn't being cheated." However, at a meeting with reporters yesterday, Waigel made clear that while he wanted to discuss with Treasury Secretary Nicholas F. Brady the methods of accounting for war costs, the information would be used to help "pull the rug out from under the unnecessary domestic debate stirred by the opposition in Germany."

"It is important that the U.S. administration and public be absolutely clear about the nature and extent of the German commitment and that our reliability not be questioned," he said. "Also, because there is domestic debate in the U.S. Congress and heated debate in Germany about this issue, it is important that there be a clear exchange of information among friends so that the cost estimates and actual costs are known."

Staff writers Ann Devroy and R. Jeffrey Smith contributed to his report.