Wednesday, October 18, 1995 UNITED NATIONS (Reuter) -- France, the United States and Britain plan to join the South Pacific nuclear-free zone after France completes its current round of controversial tests at the Mururoa and Fangataufa atolls, according to a U.S. official. The Western allies are to sign three protocols to the 1985 South Pacific Nuclear Free Zone (SPNFZ) treaty, also known as the Treaty of Raratonga, which commits them not to station nuclear weapons in the region and not use or threaten to use nuclear explosive devices, the official said Wednesday. The move, expected to be announced by the three governments before Monday, is an apparent response to the worldwide denuncation over French nuclear testing and an effort by France's allies to help Paris begin to rebuild ties with South Pacific nations. Paris is also expected to close its South Pacific test facilities once it completes its current round of blasts in May, diplomats said. Russia and China, the other two acknowledged nuclear powers, have signed two of the three protocols and South Pacific countries have been trying to get the United States, Britain and France to sign the protocols for years. The U.S. official, who spoke on condition of anonymity, stressed that Washington's decision was an effort to follow through on commitments made during last spring's Nuclear Non-Proliferation Treaty conference, when the NPT was extended indefinitely. "It is to show our bona fides to the non-nuclear weapon states in regard to our commitment toward nuclear disarmament," he said. All five nuclear powers have pledged to sign a comprehensive test ban treaty by the end of 1996. But the United States and at least one other nuclear power is pushing toward completing negotiations on the text by April in hopes it can be signed about September, before the 1996 General Assembly session, diplomats said. The new moves come shortly before more than 140 presidents and prime ministers are due to speak to the U.N. General Assembly, beginning Sunday, and some announcement may be made at that time. France ended a 1992 moratorium on testing last month with a blast at Mururoa. It staged a second explosion on October 2 at the Fangataufa atoll and plans up to six more before ending testing forever. French President Jacques Chirac says they are vital to check the safety and efficiency of France's arsenal. The 16-nation South Pacific Forum earlier this month cut diplomatic ties with France in a largely symbolic act of retaliation after France's second test at Fangataufa Atoll. But individual nations did not sever formal ties with Paris, although relations between France and almost every country in the South Pacific has been strained. Australia, for example, blocked a French bid for a major defense contract in August, prompting France to stop one of its electricity companies from investing in Australia and to threaten sanctions on imports of Australian uranium and coal. Many nations believe the NPT would not have been made permanent unconditionally last spring had it been known that France as well as China planned further tests. China has conducted two nuclear tests this year, the most recent in mid-August at its main testing site in its northwestern Xinjiang region.