The fate of the World Trade Organization's top court was effectively sealed on Monday after the United States said it would not back a proposal to allow it to continue, trade officials said, although the WTO chief vowed to find a solution.

The Trump administration has been blocking appointments to the WTO's seven-member Appellate Body that rules on trade disputes for more than two years, with U.S. officials saying the court had gone beyond its remit.

The Appellate Body needs a minimum of three judges to function but the terms of two of the three remaining members of the appeals panel expire on Tuesday and there are no replacements in sight because of the U.S. blocking strategy.