Syrian government forces and rebels on Friday exchanged retaliatory attacks in Aleppo where the United Nations is pushing for a temporary truce to allow badly needed humanitarian aid into the divided city.
Regime jets mounted a series of airstrikes on opposition-held districts in the southern and eastern parts of Aleppo, the Syrian Observatory for Human Rights, a monitoring group, said without reporting casualtuies.
Fierce fighting was going on near a rebel-held military complex in south-western Aleppo, the watchdog added.
Meanwhile, shells fired by rebels landed in regime-controlled districts in the western section of Aleppo, leaving an unspecified number of people injured, said the Britain-based Observatory that relies on a network of activists inside Syria.
Syrian state television confirmed the shelling, blaming it on what it called "terrorists" in a reference to rebels fighting to oust Syrian President Bashar al-Assad.
The broadcaster said an unspecified number of civilians were injured.
Earlier on Friday, the rebels fired a US anti-tank missile (TOW) on a gathering of Syrian soldiers in western Aleppo, killing and injuring at least six, according to the Observatory.
The violence comes a day after Russia, a major ally of al-Assad, said it was ready to conduct a 48-hour humanitarian ceasefire next week in Aleppo in response to a UN call for a truce.
Russia has been carrying out an air campaign in Syria in support of al-Assad since September 2015.
Aleppo, Syria's pre-war commercial hub, has been divided between al-Assad's forces in the west and rebels to the east since fighting erupted in mid-2012 for control of the city.
In recent months, local activists and foreign rights groups have accused al-Assad's forces and allied Russians of using banned weapons against civilians in opposition-held areas in Syria.
Activists and a local doctor alleged on Friday that a hospital in a besieged rebel area near Damascus was hit by napalm bombs.
“The only hospital in the area of Daraya is being targeted by internationally banned weapons," an unnamed doctor said in an online video which was purported to have been shot outside the facility after it was bombed.
Other vidoes posted by activists from inside Daraya showed rubble and the hospital in flames, allegedly from a napalm attack.
The Observatory meanwhile said that unidentified helicopters dropped barrels packed with explosives in the area housing the hospital that went out of service as a result.
There was no official comment in Damascus.
Daraya has been beseiged by the government forces since 2012. Only about 8,000 people remain in Daraya, which had a population of about 80,000 before Syria's conflict that started in 2011.
On Tuesday, Human Rights Watch accused Syrian regime forces and Russia of using incendiary weapons, which burn their victims and start fires, in rebel-held civilian areas in north and north-western Syria.
The New York-based watchdog appealed on countries meeting at the Convention on Conventional Weapons in Geneva on August 29 to condemn the use of air-dropped incendiary weapons and to press Syria and Russia to immediately stop using them in civilian areas.
Napalm is used in incendiary devices and causes severe burns down to the bone.