Syria's army battled to take more ground from rebels in Aleppo on Thursday after President Bashar al-Assad said victory for his troops in the city would be a turning point in the war.
Three weeks into a major offensive to retake all of Aleppo, government troops have captured about 85% of territory rebels controlled in the city's east and were continuing to push forward.
AFP's correspondents in the city said rebel areas were facing intense bombardment.
In east Aleppo, terrified residents could be seen fleeing in the streets as heavy bombing shook opposition-held areas.
In the city's west, the explosions coming from bombing of rebel districts were so strong they shook the windows of buildings. Plumes of smoke could be seen rising from the east.
Cornered in a shrinking enclave in Aleppo's southeast, the rebels have asked for a five-day ceasefire.
Western countries have backed the call but talks between the United States and Russia -- including fresh meetings between top diplomats on Thursday -- have failed to achieve a breakthrough.
In a wide-ranging interview with Syrian daily Al-Watan published on Thursday, Assad predicted victory for his forces in Aleppo, though he admitted that would not end the country's conflict entirely.
"It's true that Aleppo will be a win for us," Assad said.
"Let's be realistic -- it won't mean the end of the war in Syria," Assad said. "But it will be a huge step towards this end."
A regime victory "will mean the transformation of the course of the war across Syria," Assad said.
Rebel forces seized control of large parts of Aleppo in 2012, dividing Syria's former commercial hub into an opposition-held east and government-controlled west.
Red Cross evacuates civilians
For years Aleppo was a key battleground in the war and important rebel stronghold, but Assad's forces have recently made a concerted push to retake the city.
In the last week government forces steadily gained ground until on Wednesday -- after a highly symbolic retreat from the Old City -- the rebels called for the ceasefire to allow thousands of civilians to evacuate.
Assad's government has said a truce is only possible after a full rebel withdrawal, and opposition fighters have rejected any talk of abandoning Aleppo.
On Thursday the army, backed by foreign fighters from Iran and Lebanon's Shia Hezbollah movement, was continuing to advance, the Syrian Observatory for Human Rights said.
The Britain-based monitoring group said there were heavy clashes in several rebel neighbourhoods, including Bustan al-Qasr, Saif al-Dawla, Zibdiya, Sukkari and Kallaseh.
All rebel areas were under heavy bombardment, it said, and opposition forces were returning fire with rockets into west Aleppo.
At least 384 civilians have been killed in east Aleppo during the offensive, while rebel fire into the west has killed at least 105 people over the same period, the Observatory says.
The assault has prompted a mass exodus from east Aleppo where at least 80,000 people have fled their homes, according to the monitor.
The International Committee of the Red Cross said on Thursday it carried out an operation overnight with Syria's Red Crescent to evacuate 150 civilians, many disabled or sick, from a health facility in the Old City.
"These patients and civilians had been trapped in the area for days because of heavy clashes nearby," said ICRC Syria delegation head Marianne Gasser.
"Many of them cannot move and need special attention and care. It must have been terrifying for them."
It was unclear how many civilians remained in rebel territory, but there were an estimated 250,000 in east Aleppo prior to the latest offensive.
Diplomatic efforts fail
A series of diplomatic efforts to stop the fighting this week have stalled, with Moscow and Washington trading accusations of blame.
Moscow is a key Assad ally and launched an air war in support of his forces last year, while Washington and other Western nations have supported rebel forces.
Russia suggested earlier this week that a deal was in the works for rebel forces to be allowed to withdraw from Aleppo to other rebel territory.
US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov met twice Thursday in Germany's Hamburg but failed to make any progress on a ceasefire, an American official said.
Their meetings, on the margins of a meeting of the 57-member Organisation for Security and Cooperation in Europe, lasted 10 minutes each and "no progress, no conclusion were reached on Aleppo," the official said.
The two had also met for about an hour on Wednesday.
Despite the apparent lack of progress, Russian Deputy Foreign Minister Sergei Ryabkov suggested a deal was still possible.
"We are close to finding common ground but I would warn against too high expectations," he was quoted as saying on Thursday by the Interfax news agency.
Six Western powers including Britain, France and the United States, as well as UN chief Ban Ki-moon, called on Wednesday for an immediate ceasefire to allow aid into the city.
Smoke rises near the Old City of Aleppo as seen from a government controlled area of the city on Thursday.