NEW YORK - The UN Security Council hopes to vote Wednesday on a resolution that could threaten Sudan and South Sudan with sanctions if they do not stop fighting, diplomats said.

China and Russia, veto-wielding permanent members, are however leading resistance to any warning of international action against the rival countries, which many fear are headed for all-out war.

Sudan on Tuesday warned its southern neighbour, which split away last year, over widening "aggression" as the South alleged fresh clashes despite an African Union peace initiative in the oil-fuelled conflict.

Khartoum charged that "South Sudan and its army are working to widen the aggression and occupy some disputed points and areas by force. Sudan cannot allow the occupying troops to impose their power."

More than a week ago South Sudanese soldiers said they had completed a withdrawal from Sudan's main oil region of Heglig, which they occupied for 10 days, while Sudan launched air strikes across the border.

In New York, a resolution drawn up by the United States calls on the two countries to "immediately cease all hostilities" and withdraw troops to their own territory, in line with the call made by the African Union.