Syrian rebels have been pushed out of a strategic district in the commercial capital of Aleppo, but fighting has continued in other parts of the city.
Hossam Abu Mohammed, a rebel commander, said that his men were still fighting in parts of Salaheddin district on Friday, after most fled under heavy bombing and advancing troops.
"We will not let Salaheddin go," Abu Mohammed of the Free Syrian Army (FSA) told AFP news agency by telephone as the third day of a government offensive to take the city raged.Rebels said clashes continued in the district and that, while the government had at least 80 tanks stationed in various parts of Aleppo, the military appeared reluctant to engage in close combat, preferring to use helicopters and fighter jets.
Sheikh Tawfiq, commander of the Nur al-Din Zinky brigade based on 15th street in Salaheddin, said the army's formidable weaponry was offset by apparently faltering morale.
"At the 10th street front line we are face-to-face with the army and can hear them make orders on their radios. We hear their commanders give orders to soldiers to advance and they keep urging them to, but the soldiers don't and are hesitant."
State television said: "Our special forces have cleansed Salaheddin district of terrorists."
State media reported that the government offensive in Aleppo had taken place on several fronts, including a neighbourhood near the airport in southeast Aleppo, several eastern districts, and a town on Aleppo's northwestern outskirts, state media said.
Despite the violence, the Red Cross delivered food and medical supplies to Aleppo, the first time one of its aid convoys managed to enter the city in several weeks.
Kassem Saadeddine, an FSA spokesperson, said that the rebel withdrawal "does not mean we are leaving Aleppo. We have military plans to fight in the city, but we cannot reveal them".
'New Syria envoy'
Diplomats at the United Nations, meanwhile, indicated on Thursday that Lakhdar Brahimi, a veteran Algerian diplomat, could be named next week to replace Kofi Annan as the joint UN-Arab League envoy to Syria.
Also on Thursday, Syrian President Bashar al-Assad appointed Wael al-Halki, the country's health minister, as Syria's new prime minister. Halki replaces Riad Hijab, who fled to Jordan and defected to the opposition earlier his week.
Joseph Kechichian, senior writer for the Gulf News newspaper, speaking to Al Jazeera from Beirut, says the Syrian president is quickly running out of options.
"His options diminish day-by-day", Kechichian said of Bashar al-Assad.
As the battle for Aleppo raged, Iran called on Thursday for "serious and inclusive" negotiations between the Syrian government and opposition. Iran made the appeal after a gathering of diplomats from like-minded states in Tehran for talks on the conflict.
In-depth coverage of escalating violence across Syria
"There will be no winner in Syria," UN Secretary-General Ban Ki-moon said in a statement read by a UN representative to the conference in Tehran.
"Now, we face the grim possibility of long-term civil war destroying Syria's rich tapestry of interwoven communities."
On Friday, the United Nations said that the number of registered Syrian refugees had topped 150,000 since the conflict began in March 2011. The total includes 50,227 in Turkey, where more than 6,000 Syrians arrived this week alone.
There are also 45,869 refuguees registered in Jordan, with 36,841 more in Lebanon and 13,587 in Iraq. The number of refugees in Iraq does not include the return of 23,228 Iraqis, who had fled the US invasion in 2003, from Syria.
Smaller numbers of refugees have also fled o Algeria, Egypt, Morocco and Greece, the UN says.
UK increases opposition support
William Hague, the British foreign minister, on Friday announced that his country was offering $7.8 million in aid to the Syrian rebels. He said that none of the money would be used for weapons.
The UK will also be intensifying its contacts with Syrian opposition political figures as well as with the Free Syrian Army, he said.
The aid was likely to include mobile phones, satellite phones and radios to warn civilians of governmen assaults and
"overcome the regime's communications blockade and ensure their message gets to the outside world", Hague said.
"I have also agreed in principle that our assistance should include lifesaving protective equipment for civilians to help those carrying out vital work in the crossfire, and this could for instance include body armour," he said.
Britain would also supply medical equipment including paramedic trauma kits, surgical equipment, field dressings, antibiotics, painkillers and water purification kits, the foreign minister said.
Diplomats at the UN, meanwhile, indicated on Thursday that the official announcement regarding the appointment of Brahimi as the UN-Arab League envoy would be made early next week.
Brahimi was the UN envoy in Afghanistan after the September 11, 2001 attacks and in Iraq after the 2003 US-led invasion.
Kofi Annan, a former UN secretary-general, said he was leaving the post because of the lack of international support for his efforts to end the 17-month Syria conflict, in which rebels say more than 20,000 people have been killed.
Annan is staying in his post until August 31.