Pushed to end what the United Nations calls the world's worst humanitarian crisis, Sudanese government envoys opened talks in Nigeria on Monday for talks with rebel leaders from the western Darfur region.

Government envoys and delegates of two insurgencies battling in Darfur met in the Nigerian capital, Abuja, for talks hosted by the African Union (search), currently led by Nigeria's President Olusegun Obasanjo.

"Let us bear in mind the suffering of the masses of women, grandparents, children as well as the refugees and displaced persons," Obasanjo told delegates in a public speech before the closed-door meeting.

"I appeal to all stakeholders to have an open mind and commence the negotiations with a recommitment to a genuine search for a solution through meaningful and reasonable conditions for peace," Obasanjo said.

Majzoub al-Khalifa Ahmad, a Cabinet minister and government delegate to the last, failed Darfur peace talks in July, led Sudan's government delegation to Nigeria's capital, Abuja, for the talks, expected to last one day.

Britain's Foreign Secretary Jack Straw flew to Sudan on, stepping up international pressure on the government.

Straw said he would discuss ways of dealing with the crisis with Sudanese President Omar el-Bashir (search) before visiting a refugee camp in the western region of Darfur where conflict between rebel groups has forced millions of people to flee their homes.

"I am keen to see for myself the situation on the ground in Darfur, and to make clear to the Sudanese Government and people the extent of British, and broader international, concern," Straw said shortly before he left Britain.

Two rebel groups, the Sudan Liberation Army (search) and the Justice and Equality Movement (search), assembled high-level delegations for the talks.

Eighteen months of conflict in Darfur have killed tens of thousands and driven 1.2 million others from their homes.

Tensions between nomadic Arab tribes and non-Arab African villagers exploded in February 2003 when the two Darfur rebel groups took up arms over what they regard as unjust treatment by the government in their struggle with Arab countrymen.

The United Nations, the United States and others accuse Sudan's government of backing pro-government Janjaweed militia in a violent ethnic-cleansing campaign of killing, rape and razing communities.

Tacudi Bashi Nyan, a top Justice and Equality Movement delegate, was guardedly hopeful the conference could achieve real gains toward peace in Darfur.

"We are optimistic, but I believe that this government hasn't demonstrated enough seriousness," Nyan told reporters on Monday.

"The government is yet to put a stop to the activities of the Janjaweed, who are still killing people and attacking people. There is no security in the area. If these things are corrected, then we can have a good atmosphere for the talks. So a lot depends on circumstance," Nyan said.

In a goodwill gesture on the eve of peace talks in Nigeria, Sudan's government said Sunday it would cut the number of official paramilitary forces operating in Darfur by 30 percent.

U.N. spokeswoman Radhia Achouri welcomed the move, saying the paramilitary Popular Defense Forces have been blamed for violence against African tribespeople in west Sudan's three Darfur states.

"It is a positive step because these forces are one of the reasons of concern for us because they are armed and have been involved in the [violent] actions we want to stop," Achouri told The Associated Press in Egypt in a telephone interview from the Sudanese capital, Khartoum.

Sudan's state minister for interior affairs, Ahmed Mohamed Haroon, said Sunday that the 30 percent reduction in the volunteer force's numbers was ordered to build confidence ahead of the African Union-sponsored peace talks, and to help implement a rarely heeded April 8 cease-fire agreement.

It is unclear how many paramilitary forces operate in Darfur, but they are believed to outnumber the more than 60,000 army and police personnel stationed throughout the region.

Haroon said further reductions will occur if rebel forces adhere to the cease-fire.

"We are not saying the security threats are now nil, but we are saying that the level of threat has decreased," Haroon told reporters in Khartoum. "We will reduce the state of alert more (if) the other side shows cooperation."

On the eve of the talks, Obasanjo suggested African Union troops be used to help disarm both sides in the conflict.

More than 150 AU troops from Rwanda are currently in Darfur protecting some 80 union monitors observing the largely ignored cease-fire. Another 150 soldiers from Nigeria are expected to arrive in coming weeks.

While the troops' mandate does not spell out how far they can go to protect targeted civilians, Obasanjo, the current AU chairman, said Sunday that the soldiers and Sudanese government "must work together to garrison the rebels and put them somewhere where their arms can be collected."

"While that is happening, the government of Sudan must weigh heavily" on Arab militia known as the Janjaweed to disarm, Obasanjo said in an interview broadcast on state television. "The Janjaweed have been ... armed by the government."

Khartoum has repeatedly denied it is supporting the Janjaweed, but the United Nations said Friday that the Sudanese government has acknowledged they have "control" over some Janjaweed fighters in the region.

The rebels walked out of the last round of talks in Ethiopia on July 17, accusing the government of ignoring existing peace accords.