Updated

U.N. Secretary-General Kofi Annan flew to Ethiopia Thursday to urge a crucial international conference to break the deadlock over worsening violence in Sudan's Darfur region.

Annan wants U.N. peacekeepers to replace a beleaguered African force in Darfur and is convening the meeting of key African, Arab, European countries in a effort to win action on the killings of ethnic Africans there before he leaves office on Jan. 1.

Senior officials from the African Union, the Arab League, the European Union, Sudan, the United States, China, Russia, Egypt, France and a half-dozen African countries planned to attend.

Click here to go to FOXNews.com's Africa Center.

In recent days, pro-government militiamen have stepped up attacks on villages in Darfur, killing dozens of people, international observers said Wednesday. In one raid, janjaweed militiamen — backed by government troops — forced children into a thatched hut, then set it ablaze, killing parents who tried to rescue the children, rebels said.

Speaking on Wednesday in neighboring Kenya, Annan said the United Nations still wants to replace the 7,000-member African Union mission in Darfur with some 20,000 U.N. peacekeepers, something the Sudanese government strongly opposes.

Human Rights Watch has called for a major increase in the Darfur peacekeeping force to stop the growing number of attacks on civilians.

The New York-based advocacy group said it has documented renewed aerial bombing of civilians both in Darfur and inside neighboring Chad since late October.

"We have not given up the idea of strengthening the force in Darfur," Annan said. "We need to continue our efforts to calm Darfur ... the border area between Chad and Sudan is very fragile and volatile."

The Sudanese army has denied any connection to janjaweed attacks, saying the claims were politically motivated.

Violence has marred the vast, arid Darfur region since 2003, when rebels stemming from ethnic African tribes took up arms against the Arab-dominated central government. Khartoum is blamed for having unleashed the janjaweed militias in response. The militiamen are accused of many of the atrocities in a conflict that has killed some 200,000 people and chased 2.5 million from their homes.

Some in Darfur say the government has let loose janjaweed forces in Darfur recently to put down an umbrella coalition of rebels, the National Redemption Front, which has rejected a peace deal and clashed with government forces.

The African Union said at least 30 people were killed and 40 wounded in the janjaweed raid Saturday in the north Darfur town of Sirba, and that attacks were also reported nearby.

"We're seeing a regional war against civilians, with armed groups on both sides of the border actively supported or tolerated by the Sudanese and Chadian governments," Peter Takirambudde, Africa director at Human Rights Watch, said in a statement. "The high-level meetings in Ethiopia must produce a clear plan for immediate deployment of international troops to protect civilians in Darfur and eastern Chad."

The aid agency Medecins Sans Frontiers has reported that thousands of people have fled their homes and refugee camps in Darfur. The agency said it was also increasingly difficult to provide aid to the victims because of the violence.