TOKYO, SEPT. 14 (FRIDAY) -- Japan pledged to expand substantially its contribution to the U.S.-led moves against Iraq today, acting in the wake of sharp criticism by some Americans that it was not doing enough to help.

The offer of $4 billion in military and economic aid, which was announced after a cabinet meeting, followed rising complaints by U.S. officials and members of Congress that Japan was offering only meager support for the U.S. response to Iraq's invasion of Kuwait.

Chief Cabinet Secretary Misoji Sakamoto denied that the new aid was a response to U.S. pressure. "We listened to what various countries had to say, not just the United States, and in response to world opinion we decided" to make the increase, he said. Foreign Minister Taro Nakayama told reporters that Tokyo had acted because it had concluded that the gulf crisis was likely to be prolonged.

Nevertheless, today's announcement was the latest in a series of policy changes Japan has made to augment its support for the U.S. effort in the Persian Gulf as congressional attacks have intensified. The most recent evidence of U.S. displeasure with Japan came on Thursday, when the House of Representatives voted to begin withdrawing U.S. forces from Japan unless Tokyo agrees to pay the full cost of their presence here.

Japan had promised Aug. 30 to pay $1 billion for logistical support for the U.S.-led multinational forces in the gulf. It also had committed $22 million to assist refugees from Iraq's Aug. 2 invasion of Kuwait.

Today's announcement said Japan will provide an additional $1 billion in logistical support for the anti-Iraqi forces, plus $2 billion in economic help for countries such as Egypt, Turkey and Jordan that are suffering financially as a result of the United Nations trade embargo against Iraq.

Of the economic assistance, $600 million will be available immediately in the form of emergency commodity loans carrying a minimal interest rate of 1 percent and payable over 30-years, Japanese officials said.

U.S. Ambassador Michael Armacost welcomed the decision, saying in a prepared statement that "this decision clearly demonstrates that Japan is a full partner" in the international effort to face down Iraq.

Congressional charges that Japan was doing less than its share to support the anti-Iraqi effort in the gulf intensified during the last week, with members noting that Japan is considerably more dependent than is the United States on Middle Eastern oil.

Congressional critics warned that U.S.-Japanese relations might deteriorate seriously if the American public perceived that Tokyo's contribution was not commensurate with its interests in the gulf. At the same time, the General Accounting Office released a study that concluded that Japan had not contributed heavily to the 1987 U.S. naval operation that guaranteed oil exports from Kuwait when the Iran-Iraq war threatened Kuwaiti tankers.

Also last week, Saudi Arabia and Kuwait pledged multi-billion dollar packages for the current gulf effort, drawing expressions of appreciation from U.S. officials that contrasted with the criticism toward Tokyo.

The new aid represents a victory for Kaifu's strenuous efforts to overcome opposition to helping the military venture in the gulf. In part because of Japan's antimilitarism and in part because of resistance by its powerful bureaucrats to new spending, the Kaifu government has fought a long, messy internal debate over how to help the U.S.-led operation.

Until recently, Japanese officials were dismissing U.S. complaints as reflecting a misunderstanding of the political situation here. Japan's post-war constitution bars its military from roles overseas, and officials here have voiced fears that many Asian countries would become disturbed over any evidence that Tokyo was moving toward a military role.

Japanese officials were taken aback by the wave of anger in Congress, and today's announcement appears designed to suggest that Japan will do everything short of committing troops to the anti-Iraqi force.

{The European Community is considering providing $1.95 billion in economic aid to Jordan, Turkey and Egypt, and West German Chancellor Helmut Kohl vowed to help further, the Associated Press reported from Bonn, West Germany.}