OTTAWA -- Reform of the Bretton Woods financial institutions that have guided the world economy for a half-century will be the main focus of this year's summit of the Group of Seven leading industrial nations.


But Canadian officials preparing for the June 16-18 summit in Halifax, Nova Scotia, say there is no consensus on what to change -- or whether reform is needed at all -- in the International Monetary Fund or the World Bank.


The G-7 countries also must agree on the exact role Russia will play at the exclusive annual meeting.


President Boris Yeltsin wants full membership in what would be an expanded Group of Eight to restore Russia's status as a power, but the Chechnya crisis may hurt his case, officials said.


At their last leaders' meeting in Naples in July, the United States, Germany, Japan, Britain, France, Italy and Canada made a commitment to review postwar institutions such as the IMF and World Bank. The two institutions were created at a 1944 international conference in Bretton Woods, New Hampshire. Some industrialized nations feel it is time to modify these bodies if they are to keep serving a purpose and help bridge the gap with developing countries.


A number of private think tanks are studying the issue, including one U.S.-based group called Fifty Years Is Enough.


Canada, which took over the G-7 chairmanship from Italy on New Year's Day, is consulting other members on their views and will put a series of proposals on the table at Halifax.


But the initiative could end up very watered-down if there is no agreement, officials said.


"There is no consensus in the G-7 on the extent of the review, and whether it should cover just the Bretton Woods institutions or include the United Nations," a senior Canadian foreign ministry official said.


"There is tremendous divergence as to the breadth and scope of the review," he added. "Some think the status quo is not bad; others think more could be done for the developed world, and the institutions should be reformed to reflect that."


Yeltsin's eventual role at the Halifax summit will also be discussed at the first preparatory meeting of G-7 "sherpas," to be held in Ottawa at the end of January.


"Russia wants to turn this thing into a G-8," a Canadian official said. "They want to restore their Great Power status, and they want to be in on everything,"


Russia's participation in Halifax is expected to follow the Naples format, with Yeltsin arriving at the end of the first day of global economic talks to take part in a second day of mainly political discussions.


Some members, particularly Japan, are decidedly opposed to full Russian membership, and the Russian military attack on the capital of Chechnya could complicate Yeltsin's position.


"I don't know how Chechnya will impact," the Canadian official said. "We have been very nice in not saying anything, but how long this approach can be sustained I don't know."


While U.S. President Bill Clinton's "Open Markets 2000" proposal failed to fly at Naples, renewed efforts to liberalize world trade are expected at this summit, now that the Uruguay Round of GATT trade talks has been successfully concluded, officials said.