SYDNEY -- A split in the Howard Cabinet ranks over whether to join the United States in refusing to support an International Criminal Court is the most serious threat yet to the dream run so far enjoyed by the Canberra government.

The sudden revolt after four years of in-principal backing for this year's startup to the war crimes court follows last weekend's return by Prime Minister John Howard from cozy talks in Washington.

From a promise he gave during last year's election campaign to ratify Australia's signing of the Statute of Rome, which establishes the court, Howard now appears to be wavering toward the Bush administration's rejection of the court on the grounds it would erode national sovereignty. The change is pitting Cabinet ministers against one another and Liberals against their junior coalition partner, the National Party.