A senior U.S. envoy pushing to shore up the fragile agreement that ended a 21-year civil war in the south and strengthen peacemaking in the western Darfur region met with Sudanese unity government officials Wednesday.

The U.S. State Department's No. 2 official, Robert Zoellick, also was expected to press the government to begin peace talks with rebels in eastern Sudan, where ethnic Beja insurgents want to negotiate a political settlement.

The trip is Zoellick's fourth in six months, highlighting his increasing personal involvement in attempts to find comprehensive peace in this oil-producing nation. U.S. lawmakers are pressing the administration of U.S. President George W. Bush to ensure Sudan's President Omar el-Bashir supports efforts to end the violence in the country at the crossroads between the Middle East and Africa.

Sudan has been troubled by conflicts since independence in 1956, fueled by the accusations that the ethnic Arab-led government in central Sudan has monopolized national power and resources at the expense of outlying regions dominated by other ethnic communities.

The January agreement to end the war between the northern government and southern rebels is seen as a blueprint for ending conflicts in Darfur and eastern Sudan. It stopped Africa's longest-running civil war between the mostly Muslim north and the Christian and animist south that left about 2 million people dead.

The deal provide for an autonomous south with its own army, government and a new constitution during the six-year interim period. After the transition, the 10 southern states will hold a referendum on independence.

But implementation of the power- and wealth-sharing deal faltered after the death of the southern leader John Garang in a helicopter crash in July.

El-Bashir, under international pressure, recently formed the commission to oversee the implementation of the peace deal. That commission includes representatives of the international community.

He also formed the commission that will monitor the sharing of oil revenues as provided under the peace agreement.

But el-Bashir is yet to set up the commission that will set the north and south territories. The boundary will determine who access the vast oil and agriculture resources in the south.

El-Bashir's unity government, formed under the peace deal, includes Second Vice President Osman Ali Taha, a longtime aide who helped negotiate the southern agreement, and First Vice President Salva Kiir Mayardit, who succeeded the late Garang as leader of the former southern rebel movement.

Zoellick also wants el-Bashir to permit delivery of 105 Canadian armored personnel carriers to the African Union peacekeepers who are struggling to stabilize Darfur, where more than 180,000 people have been killed _ mainly through war-induce famine and disease. No firm figures exist on the number killed in fighting.

Darfur is the scene of one of the world's worst humanitarian crises. More than 2 million have fled their homes to escape the campaign of rape, murder, looting and arson that was unleashed by pro-government militia after the conflict erupted in February 2003, according to aid agencies.

Zoellick arrived in Khartoum a day after holding tense talks with factions of Darfur's main rebel movement, trying to get rival leaders to agree on a common negotiating position before the seventh round of peace talks resumes on Nov. 20 in Nigeria's capital, Abuja. The split within the Sudan Liberation Movement has undermined peace talks with the government and sparked more fighting in Darfur.

The separate conflict in eastern Sudan attracted international attention in January when police opened fire on peaceful protesters, killing and injuring dozens of residents of the main eastern town, Port Sudan. Rebels have since kidnapped local politicians and attacked government garrisons.