Insurgents have breached Syria's second-largest city, Aleppo, clashing with government forces, according to a Syria war monitor and fighters.

Syria state media say government troops are battling insurgents inside the country’s largest city Aleppo for the first time since 2016

Insurgents broke through government defense lines in Aleppo on Friday and entered the city’s western neighborhood with little resistance.

The advance on Aleppo followed a shock offensive launched on Wednesday, as fighters swept through villages and towns.

The lightning assault on Aleppo by the Islamist militant group Hayat Tahrir al-Sham abruptly redrew the front lines of Syria’s civil war.

Syrian armed rebels have entered Aleppo just three days into their surprise offensive, marking the first time they have set foot in the country’s second largest city since government forces recaptured the city in 2016.

Syrian rebels have reportedly breached the city of Aleppo itself, according to open source analysts and the Syrian Observatory for Human Rights, as thousands of insurgent fighters make startling advances in their surprise offensive against President Bashar al-Assad's regime in northwestern Syria.