US Deputy Secretary of State Robert Zoellick addresses a news conference in Khartoum

Sudanese officials have told Deputy Secretary of State Robert Zoellick they are doing all they can to stop the bloodshed in the war-ravaged Darfur region of western Sudan.  Mr. Zoellick arrived in Sudan to begin a two-day visit aimed at pressuring Khartoum to end the conflict in Darfur and to begin implementing an accord, which ended a separate war in the south.

At their meeting in Khartoum, Sudanese Vice President Ali Osman Taha told the second-ranking U.S. diplomat that the Sudanese government is working diligently to stop the violence in Darfur.

Mr. Taha has given such assurances before about his government's effort to end the conflict in western Sudan, which has raged for more than two years and has killed an estimated 180,000 people.

A spokeswoman for the U.S. Embassy in Khartoum, Elizabeth Colton, says Mr. Zoellick was clear in conveying the U.S. demand for the Sudanese government to live up to its past promises.

"Deputy Secretary Zoellick said that he is assuming that this is what they are going to do and also that this is what has to be done," she said.  "He kept emphasizing that we are at a time where there could be very positive things happening here or there could be a downward spiral."

At a donors conference for Sudan in Oslo, Norway earlier this week, the United States pledged nearly $2 billion over the next two years to help the country recover from a separate, 20-year-long civil war in the south.

Mr. Zoellick, who represented the United States at the conference, stressed that future aid for Sudan would depend on how quickly the Arab-dominated government in Khartoum can resolve the Darfur crisis.

The United States and other countries have voiced fears that continued fighting in Darfur between African rebels and Sudanese troops backed by the pro-government Arab militia, will unravel the hard-won North-South accord signed in January. 

The agreement signed by Khartoum and the southern rebel Sudan People's Liberation Movement included provisions for power and wealth sharing.  But implementing the accord has barely begun and the deal remains extremely fragile.

Meanwhile, foreign aid workers in Darfur say conditions have improved little for the nearly two million people displaced by the war.  Workers continue to accuse Khartoum of deliberately restricting access to many parts of the vast desert region. 

They also say the government has done little to rein in the Janjaweed militia, which Washington says has committed acts of genocide against African civilians in Darfur.

Mr. Zoellick says the Bush administration believes the Sudanese government and southern rebels cannot commit to achieving peace without addressing the violence in the western region.  He says the failure of the peace accord would mean catastrophe for Sudan.

On Friday, the deputy secretary of state is planning to travel to Rumbek, the temporary southern capital, for talks with southern rebel leader, John Garang. 

He will, then, visit a refugee camp in El Fasher in Darfur, where he is expected to meet with aid workers and highlight the need for a speedy resolution to the war.