Thousands of civilian cars were fleeing the Syrian city of Aleppo from the main Khanasir Athriya intersection out of the city hours after insurgents overran main neighbourhoods, three residents told Reuters.

They were mostly heading to Latakia and Salamiya, they said, with the main Damascus-Aleppo highway closed.

The Syrian military said on Saturday that rebels had entered large parts of Aleppo city during an offensive in which dozens of soldiers had been killed, forcing the army to redeploy — the biggest challenge to President Bashar al-Assad in years.

The surprise attack led by the Islamist Hayat Tahrir al-Sham has jolted the front lines of the Syrian civil war that have largely been frozen since 2020, reviving fighting in a corner of the fractured country near the Turkish border. The army said it was preparing a counteroffensive to restore state authority.

The Syrian army command's statement was the first public acknowledgement by the military that rebels had entered Aleppo, which had been under full state control since government forces backed by Russia and Iran drove out rebels eight years ago.

Army planning counterattack

"The large numbers of terrorists and the multiplicity of battlefronts prompted our armed forces to carry out a redeployment operation aimed at strengthening the defence lines in order to absorb the attack, preserve the lives of civilians and soldiers, and prepare for a counterattack," the army said.

The army said that the rebels had entered large parts of Aleppo but army bombardment had stopped them from establishing fixed positions. It promised to "expel them and restore the control of the state ... over the entire city and its countryside."

Two rebel sources said the insurgents had also captured the city of Maraat al Numan in Idlib province, bringing all of that province under their control, in what would be another significant blow to Assad.

The fighting revives the long-simmering Syrian conflict as the wider region is roiled by wars in Gaza and Lebanon, where a truce between Israel and the Iran-backed Lebanese group Hezbollah took effect on Wednesday.

The attack was launched from insurgent-held areas of northwestern Syria that remain outside Assad's grasp.

Warplanes strike on outskirts of Aleppo

Two Syrian military sources said that Russian and Syrian warplanes targeted insurgents in an Aleppo suburb on Saturday.

Speaking on Friday, Kremlin spokesperson Dmitry Peskov said Moscow regarded the rebel attack as a violation of Syria's sovereignty. "We are in favour of the Syrian authorities bringing order to the area and restoring constitutional order as soon as possible," he said.

The Syrian Civil Defence, a rescue service operating in opposition-held parts of Syria, said in a post on X that Syrian government and Russian aircraft carried out airstrikes on residential neighbourhoods, a gas station and a school in rebel-held Idlib, killing four civilians and wounding six others.

The two Syrian military sources said Russia has promised Damascus extra military aid that would start arriving in the next 72 hours. Authorities closed Aleppo airport and roads to the city, the two military sources and a third army source said.

The Syrian army has been told to follow "safe withdrawal" orders from the main areas of the city that the rebels had entered, the three military sources said.

Iran's role in the region

The rebels, including factions backed by Turkey, said on Friday their fighters were sweeping through various Aleppo neighbourhoods.

Mustafa Abdul Jaber, a commander in the Jaish al-Izza rebel brigade, said their speedy advance had been helped by a lack of Iran-backed manpower to support the government in the broader Aleppo province.

Iran's allies in the region have suffered a series of blows at the hands of Israel as the Gaza war has expanded through the Middle East.

Iranian Foreign Minister Abbas Araqchi, in a phone call with his Syrian counterpart on Friday, accused the United States and Israel of being behind the insurgent attack.

The opposition fighters have said the campaign was in response to stepped-up strikes in recent weeks against civilians by the Russian and Syrian air forces on areas of Idlib province, and to pre-empt any attacks by the Syrian army.

Opposition sources in touch with Turkish intelligence said Turkey, which supports the rebels, had given a green light to the offensive. Turkish officials were not immediately available to comment on Saturday.

Turkey's Foreign Ministry said on Friday that the clashes between rebels and government forces had resulted in an undesirable escalation of tensions.

In a statement, spokesperson Oncu Keceli said that avoiding greater instability in the region was Turkey's priority, adding that Ankara had warned that recent attacks on Idlib undermined the spirit and implementation of de-escalation agreements.