UNITED NATIONS -- The United Nations is set to celebrate its 50th anniversary this weekend with a diplomatic extravaganza that is turning New York inside out.


Kings, presidents and prime ministers from more than 150 member states are converging on the city, turning it into the world's diplomatic and political capital.


The celebrations come at a time when the United Nations is experiencing the worst financial crisis since it was formed after World War II. It is owed $3.7 billion by members for its regular budget and peacekeeping.


Of the 15 countries that pay more than 80 percent of the budget, the United States owes the most, $1.4 billion, followed by Russia with about $500,000 and the Ukraine with about $238,000.


New York Mayor Rudolph Giuliani is hosting gala events for the leaders Saturday before they begin their speeches the next day. Each address is supposed to last only five minutes, which would be a record in brevity for any of the leaders.


But if everyone speaks only two minutes longer, General Assembly President Freitas do Amaral said, "we would have an extra 6 1/2 hours worth of speeches."


Guests range from U.S. President Bill Clinton and Russian President Boris Yeltsin to the kings of Jordan, Morocco and Swaziland, the prime ministers of China, Britain, France and Japan and the two captains regent of tiny San Marino.


Cuban President Fidel Castro is also coming -- but both Giuliani and Clinton have excluded him from their respective dinners for the world leaders.


Not coming to New York by their own choice are the heads of state of Iraq, Libya, North Korea and Iran, countries either subject to UN sanctions or with rocky relations with the United States, or both.


The only European country whose leader appears to have snubbed the event is Germany, despite Bonn's quest for a seat on the 15-nation UN Security Council. Chancellor Helmut Kohl is sending his foreign minister, Klaus Kinkel.


Much of the political action will take place beyond the confines of the cavernous UN General Assembly hall.


Clinton has separate meetings scheduled with Yeltsin and China's Jiang Zemin. French President Jacques Chirac is due to confer with Algerian President Liamine Zeroual against the background of a bombing campaign in France by Algerian Islamic extremists who threaten even worse if the meeting is held.


British Prime Minister John Major and Argentine President Carlos Menem are expected to hold the highest-level encounter between leaders of their countries since they went to war over the Falkland Islands in 1982.


The gathering is the biggest get-together in diplomatic history, eclipsing the 15th General Assembly session in 1960, which entered UN folklore mainly due to the shoe-banging antics of then-Soviet leader Nikita Khrushchev.


Back then, the United Nations had about 100 members, compared with 185 today, and security was much more relaxed.


Half a dozen U.S. and UN agencies are giving protection this weekend, in addition to the usual complement of personal bodyguards.