By Ellen Francis and Lisa Barrington
BEIRUT (Reuters) - Syrian President Bashar al-Assad appeared close to victory in Aleppo on Wednesday, but United Nations and rebel officials denied that an operation to evacuate fighters and civilians from the city had been completed.
The Syrian Observatory for Human Rights, a group that monitors the war, said Assad had control of Aleppo after the last fighters were brought out of the city and only one small position on the western outskirts remained in rebel hands.
But a U.N. official in Syria, asked about the Observatory report, told Reuters: "That is not something we can confirm. Evacuations are still ongoing."
A spokesman for the Free Syrian Army rebel alliance, Osama Abu Zaid, told an Arab news channel that evacuations had been slowed by bad weather and would continue into the night.
Aid workers also said the evacuation was not yet finished, while in Washington the State Department said it could not confirm that all rebel fighters had left.
For Assad, the biggest prize of Syria's nearly six-year-old civil war would be the fighters' departure, ending a battle which the Observatory said had cost the lives of 21,500 civilians in and around the city.
Earlier, buses carrying civilians and fighters began leaving Aleppo's last rebel-held enclave after being held up for a day.
People had been waiting in freezing temperatures since the evacuation hit problems on Tuesday, when dozens of buses were stuck in Aleppo, and the evacuation of two Shi'ite villages outside the city, al-Foua and Kefraya, also stalled. Rebels and government forces blamed each other for the hold-up.
Charity Save the Children said heavy snow was hampering efforts to help injured children.
"Many have had to have limbs amputated because they did not receive care on time, and far too many are weak and malnourished," a statement said.
One 5-month-old girl had two broken legs, a broken arm and an open wound in her stomach, the statement said.
Many of those who had escaped Aleppo were sleeping in unheated buildings or tents in sub-zero temperatures. Children have been separated from their parents in the chaos as they run to get food when they get off the buses, the charity said.
With obstructions to the evacuation plan apparently overcome, a news service run by the Lebanese group Hezbollah said 20 buses carrying fighters and their families moved from east Aleppo on Wednesday toward rebel-held countryside. Syrian TV said a number of buses arrived in government-controlled parts of the city from al-Foua and Kefraya.
Government forces had insisted the two villages must be included in the deal to bring people out of east Aleppo.
So far, about 30,000 people have been evacuated from Aleppo, according to the International Committee of the Red Cross.
Aleppo's rebel zone is a wasteland of flattened buildings, rubble and bullet-pocked walls, where tens of thousands lived until recent days under intense bombardment even after medical and rescue services had collapsed.
Rebel-held parts of the once-flourishing economic center with its renowned ancient sites have been pulverized in a war which has killed more than 300,000, created the world's worst refugee crisis and allowed for the rise of Islamic State.
But in the western part of the city, held throughout the war by the government, there were big street parties on Tuesday night, along with the lighting of a Christmas tree, as residents celebrated the end of fighting.
Syrian state TV said on Wednesday the army would enter the last remaining rebel-held sector of Aleppo as soon as all fighters had left. That would be a major victory for Assad, and his main allies Iran and Russia, against rebels who have defied him in Syria's most populous city for four years.
U.N. MONITORS EVACUATION
The United Nations had said it had sent 20 more staff to east Aleppo to monitor the evacuation.
Assad's government is backed by Russian air power and Shi'ite militias including Lebanon's Hezbollah movement and Iraq's Harakat al-Nujaba. The mostly Sunni rebels include groups supported by Turkey, the United States and Gulf monarchies.
For four years, the city was split between a rebel-held east and government-held west. During the summer, the army and allied forces besieged the rebel sector before using intense bombardment and ground assaults to retake it in recent months.
Russian air strikes enabled Assad's forces to press the siege of eastern Aleppo to devastating effect. Shi'ite militias from as far afield as Afghanistan also played an important role.
But even with victory in Aleppo, Assad still faces great challenges. While he controls the most important cities in western Syria and on the coast, armed groups including Islamic State control swathes of territory elsewhere in the country.
(Additional reporting by Stephanie Nebehay; Writing by Angus McDowall and Peter Millership; Editing by Giles Elgood)