ALEPPO (SYRIA) - Syria's regime on Sunday pursued a relentless assault of rebel-held east Aleppo that has killed more than 100 civilians in recent days, as the UN's peace envoy arrived in Damascus for talks.
Air strikes, artillery fire and barrel bomb attacks continued through the night and into Sunday morning as the army pressed a new offensive that has been condemned by Washington and the United Nations.
An AFP journalist in eastern Aleppo said streets were deserted, with only ambulances and rescue workers moving through battered neighbourhoods.
Damascus launched the renewed assault on east Aleppo on Tuesday in a bid to seize full control of the divided city, a key battleground in Syria's five-year civil war.
The Syrian Observatory for Human Rights, a Britain-based monitor of the war, said early on Sunday that 54 people had been killed in the previous 24 hours, most of them civilians.
That brought to 103 the number of civilians killed, including 17 children, since the regime renewed its bombardment of Aleppo, it said.
The Observatory also reported heavy fighting between regime forces and rebels as the army sought to gain ground in the Bustan al-Basha and Sheikh Saeed neighbourhoods of the rebel-controlled east.
More than 300,000 people have been killed in Syria since the conflict began with anti-government protests in March 2011. Successive international attempts to find a peaceful resolution to the war have failed.
Staffan de Mistura, the UN's peace envoy for Syria, arrived in Damascus on Sunday for talks with Foreign Minister Walid al-Muallem that were likely to address the latest violence.
International concern has grown over the renewed assault, which has forced the closure of hospitals and schools, destroyed rescue worker facilities, and left residents cowering in their homes.
On Saturday, Washington slammed what it described as a "heinous" operation.
- UN 'appalled' by violence -
US National Security Advisor Susan Rice said Washington condemned "in the strongest terms these horrific attacks against medical infrastructure and humanitarian aid workers".
"The Syrian regime and its allies, Russia in particular, bears responsibility for the immediate and long-term consequences these actions have caused in Syria and beyond."
Moscow began a military intervention in support of President Bashar al-Assad's government last year.
It says it is not involved in the current assault on Aleppo, concentrating its firepower on opposition and jihadist forces in neighbouring Idlib province instead.
But Damascus and its allies have made clear they want rebels expelled from eastern Aleppo, which fell from regime control in mid-2012.
More than 250,000 people remain in the east of the city, which has been sealed off since government forces surrounded it in mid-July.
On Saturday, UN officials said they were "extremely saddened and appalled by the recent escalation in fighting in several parts of Syria."
Humanitarian coordinator for Syria Ali al-Za'atari and regional humanitarian coordinator Kevin Kennedy also said they had shared a plan to deliver aid to east Aleppo and evacuate the sick and wounded.
"It is imperative all parties agree to the plan and allow us to secure immediate, safe and unimpeded access to provide relief to those most in need," they said in a joint statement.
- Family of six killed -
Once Syria's economic powerhouse, Aleppo has been ravaged by the war.
No aid has entered east Aleppo since July, and the government siege has led to food and fuel shortages, while sustained bombardment has forced schools and hospitals to close.
In mid-October, Russia said it was halting its strikes on Aleppo, and organised a series of brief ceasefires intended to encourage civilians and surrendering rebels to evacuate the east.
But few did so, and the UN said the short windows were insufficient for it to secure security guarantees for aid deliveries or evacuations.
The renewed bombing has particularly affected medical and rescue facilities in the east, with shelling on Friday destroying one of the last hospitals in rebel-held Aleppo.
Staff were also forced to evacuate the east's only children's hospital because of repeated attacks, removing babies from incubators.
Among those killed in the overnight bombing Sunday were a couple and their four children who died in a barrel bomb attack in the Sakhur neighbourhood, the Observatory said.
Activists circulated footage they said showed the children, in which the four siblings lay lifeless on a stone floor, among them a little girl with her hair in pigtails wearing a blue jumper with a cartoon animal on it.