China can play a constructive role in helping resolve the continuing crisis in Darfur, Washington's emissary to war-torn Sudan said Thursday, as he urged Beijing to undertake even "more forceful measures." US special envoy to Sudan Andrew Natsios told a congressional panel that Beijing, with its extensive economic ties in Sudan, may enjoy special leverage in being able to pressure the recalcitrant Khartoum government.

"The Chinese have been largely supportive of our efforts to resolve the Darfur situation through peaceful means," Natsios said at a hearing of the House Foreign Relations Committee.

His remarks came after the United States confirmed plans for wide-ranging financial and other sanctions against Sudan if Khartoum does not follow through on a deal to deploy a 20,000-strong African Union-UN force in Darfur, under a UN-brokered agreement.

The US sanctions package is part of a three-tiered "Plan B" of coercive steps that Washington has repeatedly threatened to launch if Sudanese President Omar al-Beshir's Arab-led government does not halt a campaign of repression unleashed to halt an ethnic African rebellion that has left 200,000 dead and 2.5 million homeless in Darfur since 2003.

Natios said he was encouraged, after traveling to Beijing last month, of China's desire to play an affirmative role in Darfur, and said he assured Chinese leaders that the Washington shares the same goals.

"We confirmed with them our position that our interests in Darfur are solely humanitarian, and we have no economic or military interests behind our policies," Natsios said.

"We also made clear that we are not pursuing regime change in Sudan," Natsios said, "unless the people vote for a new government in free and fair elections."

The diplomat praised China's recent "vital and constructive" role trying to pressure Sudan to allow the UN and AU troops to enter Darfur, but said China could do even more.

"While we welcome and encourage China's efforts to apply diplomatic pressure on the government of Sudan, we will look to Beijing to join with international community in applying more forceful measures, should Khartoum remain intransigent," the envoy said.

"China's substantial economic investment in Sudan gives it considerable potential leverage, and we have made clear to Beijing that the international community will China to be part of the solution," said Natsios.