MOGADISHU, Somalia (AP) – Islamic fighters retreated Tuesday as Somali government and Ethiopian troops advanced on three fronts in a decisive turn in the battle for control of this Horn of Africa nation.

Somalia’s internationally backed government called on the Council of Islamic Courts to surrender and promised amnesty if they lay down their weapons, spokesman Abdirahman Dinari said from Baidoa, the seat of the interim administration.

Ethiopian Prime Minister Zenawi, whose military openly joined the war Sunday after weeks of quietly aiding the Somali government, said his forces had completed about half their mission.

“As soon as we have accomplished our mission – and about half of our mission is done, and the rest shouldn’t take long – we’ll be out,” Mr. Meles told reporters in the Ethiopian capital, Addis Ababa.

He also claimed Islamic militiamen had suffered heavy casualties, citing internal reports from Ethiopia’s military. “I hear reports of close to 3,000 injured in Mogadishu’s hospitals … and well over 1,000 might have died,” Mr. Meles said.

The U.N. Security Council called an emergency meeting Tuesday to be briefed on the fighting. An African force authoritized by the Security Council on Dec. 6 to protect the Somali government has not yet been deployed.

The Dec. 6 resolution, sponsored by the United States and co-sponsored by the council’s African members, also partially lifted an arms embargo on Somalia so the regional force could be supplied with weapons and military equipment.

Both sides have claimed to have killed hundreds of their enemy, but independent observers have not been given access to the battlefields to check on the reports.

Sheik Sharif Sheik Ahmed, leader of the Council of Islamic Courts’ executive body, said the group had told its troops to withdraw from some areas.

“The war is entering a new phase,” he said. “We will fight Ethiopia for a long, long time and we expect the war to go everyplace.”

Ahmed declined to explain his comments in greater detail, but some Islamic leaders had threatened a guerrilla war to include suicide bombings in Addis Ababa. He also accused Ethiopian troops of massacring 50 civilians in the central town of Cadado.

Ethiopian officials were not immediately available to respond to the allegation.

Patrick Mazimhaka, deputy chairman of the African Union Commission, expressed support for Somalia’s government and defended Ethiopia’s military advances.

“If Ethiopia feels sufficiently threatened, then we recognize the right of Ethiopia to defend itself if it thinks its sovereignty and its security are under direct threat,” he said.

The United Nations helped set up the acting government in the arid, impoverished nation two years ago, but the administration was not able to extend its influence outside Baidoa, which is about 140 miles northwest of Mogadishu, the country’s nominal capital.

Somalia has not had an effective government since warlords overthrew a longtime dictator in 1991, plunging the country into anarchy. Warlords remained largely in control until this summer, when the Islamic movement seized power in Mogadishu and much of southern Somalia.

Experts fear the conflict could engulf the region. John Prendergast, a senior adviser with the International Crisis Group, said the war “dangerously escalates regional tensions and leaves the Horn of Africa less secure than it has been in a long time.”

Some analysts also fear the Islamic movement hopes to make Somalia a third front, after Afghanistan and Iraq, in militant Islam’s war against the West.

The group’s often severe interpretation of Islam is reminiscent, to some, of Afghanistan’s Taliban regime – ousted by an American-led campaign in late 2001 for harboring Osama bin Laden. The U.S. government says four al Qaeda leaders, believed to be behind the 1998 bombing of the U.S. embassies in Kenya and Tanzania, are now leaders in the Islamic militia.

The African Union, Arab League and a regional group known as IGAD were scheduled to take up Somalia at meeting Wednesday designed to restart peace negotiations between the Somali government and the Islamic movement.

But Mr. Ahmed rejected any suggestion of peace talks and appeared unbowed by his group’s losses.

Skirmishes were continuing Tuesday.

A witness in the town of Bur Haqaba reported hearing explosions nearby after two Ethiopian jets flew overhead.

“I saw two helicopters, I heard the sounds of bombs at Lego village,” Mohamed Abdulle Siidi said by telephone. The account could not be confirmed.

Islamic militiamen withdrew more than 50 miles to the southeast from Daynuney, a town just south of Baidoa. The retreat along the western front followed the bombing by Ethiopian jets of the country’s two main international airports.

Advancing government and Ethiopian troops captured Bur Haqaba, one of the Islamists’ main bases after it was abandoned early Tuesday.

“We woke up from our sleep this morning and the town was empty of troops, not a single Islamic fighter,” Ibrahim Mohamed Aden, a resident of Bur Haqaba said.

Islamic fighters were also reportedly retreating on two other fronts.

On the southern front, government troops captured Dinsor, the government spokesman, Mr. Dinari, said. On the northern front, government and Ethiopian troops entered Bulo Barde, where just two weeks ago an Islamic cleric said anyone who did not pray five times a day would be executed.

Government and Ethiopian troops also were headed for Jowhar, 55 miles north of Mogadishu, after driving Islamic troops from Bandiradley, Adadow and Galinsor.

But Meles has said he does not intend to keep his forces in Somalia long, perhaps only a few weeks. He has told visiting dignitaries that his goal is to severely damage the Islamic movement’s military capabilities and allow both sides to return to peace talks on even footing.

Mr. Meles said he would not send troops into Mogadishu, but instead encircle the city to contain the Islamic forces.

Ethiopia and Somalia have fought two wars over their disputed border in the past 45 years, and the Islamic movement has said it want to incorporate ethnic Somalis living in eastern Ethiopia, Djibouti and northeastern Kenya into a Greater Somalia.