The UN's Syria envoy said Damascus is willing to facilitate a humanitarian ceasefire by halting fire on Aleppo, where regime troops are engaged in a new offensive to encircle embattled rebels.
The comments by Staffan De Mistura on Tuesday, came as regime forces severed the main rebel supply line into Aleppo in fighting that killed more than 150 people.
As clashes raged in the area, De Mistura announced that Damascus was willing to suspend its aerial bombardment of Aleppo city for a period of six weeks.
"The government of Syria has indicated to me its willingness to halt all aerial bombing and artillery shelling for a period of six weeks all over the city of Aleppo from a date we'll announce from Damascus," De Mistura told journalists after addressing the UN Security Council.
Rebel fighters who hold parts of Aleppo but have no air power would be asked to suspend rocket and mortar fire for six weeks.
"The purpose is to spare as many civilians as possible while we try to find a political solution," the diplomat said.
The announcement was the first sign of progress for De Mistura, who was appointed UN peace envoy for Syria in July.
Last year he proposed a plan to "freeze" fighting in Aleppo in a bid to allow humanitarian access, but the proposal failed to gain much traction.
And De Mistura incurred the wrath of the opposition last week by describing President Bashar al-Assad as "part of the solution" to the country's conflict.
- Rebel supply route cut -
On the ground, meanwhile, Syrian troops effectively severed the main rebel supply route into the eastern half of Aleppo city, which is under opposition control, the Syrian Observatory for Human Rights said.
The highway runs up to the Turkish border through the town of Tal Rifaat, but regime forces now control two villages that straddle the route, effectively closing it to rebel traffic.
Aleppo city has been divided between regime control in the west and rebel control in the east since shortly after fighting began there in mid-2012.
In the surrounding countryside the situation is largely the reverse, with rebels controlling much of the area west of the city and regime forces much of the east.
Government forces advanced around the east of the city last year, but the front lines had been relatively static in recent weeks.
The severing of the highway leaves the rebels with only a long detour through the countryside available to them for resupply.
Regime forces also captured the village of Hardateen, in the countryside of Aleppo, but lost another village to rebel fighters in the area, the Britain-based Observatory said.
The fighting left more than 150 people dead, the monitor reported, including at least 70 regime forces, both army troops and foreign and local militiamen.
At least 86 opposition forces were killed, including 20 from Al-Qaeda's Syrian affiliate Al-Nusra Front.
On Monday, regime troops had also opened fire on two towns on the road to Nubol and Zahraa, government-held Shiite villages that have been under rebel siege for more than 18 months.
"The regime troops have two goals in the area: to cut the road leading from Aleppo to the Turkish border, which is the key supply road for the rebels, and to open the way to Nubol and Zahraa," Observatory director Rami Abdel Rahman said.
More than 210,000 people have killed in Syria since the country's conflict began in March 2011 with anti-government protests that spiralled into a war after a regime crackdown.
Source: AFP