Saudi Arabia warned Thursday that any military cooperation between the United States and Russia in Syria must help advance a political transition to end the war without Bashar al-Assad in power.

Foreign Minister Adel al-Jubeir told reporters he was ready to welcome US-Russian cooperation as US Secretary of State John Kerry headed to Moscow for talks on ending Syria's five-year war.

"With regards to the Russian-American cooperation in the fight against terrorism: this is something we had asked for," Jubeir told reporters following meetings at the United Nations.

But he added: "The key is really to move the situation in Syria along a political process."

The Washington Post reported that Kerry will propose setting up a joint command and control center to direct air strikes against the Islamic State and other jihadist groups, during his talks with President Vladimir Putin.

The Saudi foreign minister said Syria must move forward on a political transition that provides for an interim governing council with full power to manage state affairs and "lead to a new Syria without Bashar al-Assad in it."

"Anything that helps move the process in that direction is something that we would welcome," he added.

Russia had repeatedly called on the United States and other countries to cooperate more closely to defeat the Islamic State group and other jihadists in Syria.

Cooperation with Moscow has long been viewed with suspicion, as it would amount to acceptance of Russia's backing for the Assad regime.

Saudi Arabia is supporting various rebel groups fighting the Damascus regime, some of whom have close ties with the Al-Qaeda-affiliated Al-Nusra Front and are not considered moderates.

Under a UN plan, the political transition in Syria is to begin on August 1, with the formation of an interim body followed by the drafting of a new constitution and elections 18 months later.

But the fate of Assad remains unresolved, with the opposition demanding that he must leave power immediately.

Strikes kill 12 in rebel-held half of Syria's Aleppo
Aleppo, Syria (AFP) July 14, 2016 - Air strikes killed at least 12 civilians including children in two rebel-held neighbourhoods of Syria's divided city of Aleppo on Thursday, a monitoring group said.

Nine people were killed in the Tariq al-Bab area, and another three in the district of Salhin, both in eastern Aleppo, the Syrian Observatory for Human Rights reported.

The Britain-based group said it was unclear whether the strikes were carried out by warplanes of the Syrian government or its ally Russia.

In Tariq al-Bab, civil defence workers sifted through debris for survivors.

"A missile hit... and two whole families lost their lives," said one of them, Mohammed al-Ismael.

"We pulled four martyrs from the rubble, including children and women, and until now there are another six victims under the rubble."

The work proceeded slowly because of ongoing air strikes in the area, each raid forcing the workers to scatter and shelter in nearby buildings.

An older woman sat on the pavement watching the workers dig through the remains of a pancaked building.

"One of my children has been rescued but another one is still underneath the rubble," she told AFP.

Nearby, a distraught Mohamed Qattan dug through debris with his bare hands.

"My family are beneath the rubble," he said, calling out to them in the hope of hearing a reply.

"I was praying at the mosque when the strike happened. My wife and two of my children -- my son and daughter -- are underneath the rubble," he told AFP.

In Salhin, the strikes also wrought destruction, with video obtained by AFP of the aftermath showing smoke billowing from the front of a multi-storey building shorn of its facade.

The charred skeleton of a car, its windows blown out, sat in front of the building.

Civil defence workers battled a fire sparked by the attack, while civilians with ladders retrieved belongings from the ruins.

"Total destruction," said resident Jomaa Hassan, gesturing to a smoking building behind him.

"These are civilians: a taxi driver, a municipal worker. These are the terrorists in their eyes."

Aleppo city is divided roughly between government control in the west and rebel control in the east.

Last week, government forces advanced to within firing range of the only remaining supply route into the rebel-held east, effectively cutting it off and prompting food shortages and spiralling prices.

The International Committee of the Red Cross said Thursday that 19 trucks loaded with aid entered rebel-held Waer in the central city of Homs, the second such delivery in a month to the regime-besieged district.

More than 280,000 people have been killed in Syria since its conflict began in March 2011 with anti-government protests that were met with a regime crackdown.