TOKYO, SEPT. 18 -- Prime Minister Toshiki Kaifu has decided to dispatch Japanese personnel to the Persian Gulf in substantial numbers and has asked his cabinet to develop a deployment plan before he travels to the United States at the end of this month, government officials said today.

Concerned that Japan will face continued U.S. criticism unless it adds a sizeable human element to its financial contributions to the multinational force assembled in the gulf region after Iraq's Aug. 2 invasion of Kuwait, Kaifu will tell the Japanese people that this country must "contribute not only dollars but also sweat and manpower," said Taizo Watanabe, chief spokesman for the Japanese Foreign Ministry.

He would not predict how large a Japanese detachment might be, but estimates in the Japanese press range from several hundred to thousands of people.

Kaifu has already pledged to send 100 volunteer medical workers to the gulf region, the first 17 of whom left Tokyo today for Saudi Arabia. In addition, two Japanese airlines have pledged to send wide-body jets to Jordan to fly East Asian refugees from Kuwait back to their homes.

Contributing more manpower in a potential war zone without violating Japan's pacifist constitution will probably mean sending some kind of unarmed support force, perhaps attached to a United Nations peace-keeping mission, Watanabe said.

Kaifu is scheduled to visit New York Sept. 29-30 for a U.N. conference on children. He evidently wants to have a definite proposal before then to show Americans that Japan is not shirking in the gulf crisis and to show the Japanese that the idea was not dreamed up in Washington and foisted on Kaifu by President Bush.

"The prime minister's goal," said Watanabe, "{is} to have a completed plan in place by the time he leaves for America." Such a program would then be submitted to -- and presumably passed by -- the Diet, Japan's legislature, where Kaifu's Liberal Democratic Party has a majority of the votes.

Japanese public opinion is far from settled on how big a role the nation should play in the Western allies' efforts. Opinion polls show heavy majorities opposing the commitment of any member of the Japanese military, officially known as the Self-Defense Force. People seem uncertain when asked whether non-military Japanese personnel should be sent to the gulf.

Other Asian nations, meanwhile, are clearly apprehensive about Japan's taking a role in international military matters. Japan conquered and colonized many Asian nations in this century, and those countries have made clear their opposition to Japan's assuming an active military role anywhere.

Japan has a large stake in the Persian Gulf crisis. The country imports virtually all its oil, and about 70 percent of it comes from the Middle East.

Kaifu initially promised about $1 billion in financial support but said that Japan could not dispatch any significant numbers of people to the region. Under intense U.S. pressure, Kaifu's cabinet has now agreed to increase its financial aid to about $4 billion. But the prime minister, concerned that he will face further criticism during his trip to the United States, is apparently determined to find a way to send support personnel to the Arabian Peninsula this fall.

The Bush administration has publicly praised Japan for its financial commitment to the allied effort against Iraq and to the "front-line states" of Egypt, Turkey and Jordan. A senior diplomat at the U.S. Embassy here said the figure is satisfactory. "Four billion dollars is real money," the American said.

But the diplomat added that U.S. officials have told Kaifu that "the more Japan can do in the way of physical presence {in the gulf region}, the better."

Some members of opposition parties here have publicly opposed sending Japanese personnel to the Mideast, but the idea seems to have broad support among the dominant Liberal Democrats.

One of Kaifu's rivals for power within the Liberal Democrats, Kiichi Miyazawa, told a meeting of his party faction this week that "as the world's second-ranking economic power, it is time for Japan to find a way to get involved" in the effort in the gulf.

One proposal here calls for passage of a new law permitting Japan to send unarmed soldiers -- both active-duty and retired members of the Self-Defense Force -- as members of a U.N. peace-keeping force.

Other ideas center on increased aid to refugees in the region and the assignment of Japanese navy minesweepers to help with coastal patrol.

Meanwhile, U.N. Secretary General Javier Perez de Cuellar sought funds today for a standby peace-keeping operation, but the United Nations has not taken any concrete steps toward assembling such a force. Some nations have said they would not send troops to the gulf region except as part of a U.N. peace-keeping contingent.