The Syrian military rushed in reinforcements on Sunday to stop insurgents advancing further into the northern Hama countryside after they seized Aleppo and surrounding strategic locations in an adjacent province in a surprise offensive.

The insurgents, led by Hayat Tahrir al-Sham, took over most of Aleppo on Saturday and claimed to have entered the city of Hama.

There was no independent confirmation of their claim.

Syria Opposition
Syrian opposition fighters get on a motorcycle as others stand on top of a captured armoured vehicle in the town of Maarat al-Numan, south-west of Aleppo (Omar Albam/AP)

Rebel commander Colonel Hassan Abdulghani said separately the insurgents also took control of Sheikh Najjar, also known as the Aleppo Industrial City, north-east of the city, Aleppo’s military academy and the field artillery college to the south-west.

Iranian Foreign Minister Abbas Araghchi travels to the Syrian capital, Damascus, later on Sunday. He told reporters Tehran will back the Syrian government and army.

The swift and surprise offensive is a huge embarrassment for Syria’s President Bashar Assad and raises questions about his armed forces’ preparedness.

It also comes at a time when Mr Assad’s allies – Iran and groups it backs and Russia – are preoccupied with their own conflicts.

Syrian state television claimed government forces have killed nearly 1,000 insurgents over the past three days, without providing evidence or details.

Government air strikes overnight on Idlib city, the rebel-held bastion near Hama province and 40 miles (65km) south-east of Aleppo, killed four civilians and injured 54 others, according to the Syrian Civil Defence, also known as the White Helmets, that operates in opposition-held areas.

According to Syrian state news agency Sana and a war monitor, the army pushed back insurgents in the northern countryside of Hama province overnight.

Syria Opposition
A defaced portrait of Syrian President Bashar Assad lies on the ground in the town of Maarat al-Numan, south-west of Aleppo (Omar Albam/AP)

Britain-based opposition war monitor the Syrian Observatory for Human Rights said government reinforcements created a “strong defensive line” in the northern Hama countryside.

The observatory and Syrian state-run news network Al-Ikhbariyah also reported Russian air strikes, both in Idlib and some of the areas now under rebel control.

In his first public comments since the start of the offensive, released by the state news agency on Saturday evening, Mr Assad said Syria will continue to “defend its stability and territorial integrity against terrorists and their supporters”.

He added that Syria is able to defeat them no matter how much their attacks intensify.

The 2016 battle for Aleppo was a turning point in the war between Syrian government forces and rebel fighters after 2011 protests against Mr Assad’s rule turned into an all-out war.

After appearing to be losing control of the country to the rebels, the Aleppo battle secured Mr the president’s hold on strategic areas of Syria, with opposition factions and their foreign backers controlling areas on the periphery.