Japan's proposals on fiscal reform for the cash-strapped United Nations would gradually raise its share of the world body's ordinary budget, to 16.9 percent next year and to 19.5 percent in 2000 from the current 15.7 percent, government officials said May 27.

But if reform proposals put forward by the European Union prevail, Japan's share of the budget would exceed 20 percent next year, according to the officials, who spoke on condition of anonymity. The share of the U.N.'s budget that each of the more than 180 member states pay is revised every three years, based on such factors as fluctuations in gross national product. The new budget shares for 1998, 1999 and 2000 will be determined at the General Assembly session in the fall.

For the last three years, member countries have discussed possible changes in budget share calculations as part of efforts to revamp the U.N.'s troubled financial structure. The negotiations are now entering a critical stage ahead of the next General Assembly session.