If successful, it would be the biggest blow to foreign backed militant groups in Syria's largest city since they entered it two years ago. Aleppo, once Syria's commercial center, has been carved up into rebel- and government-controlled areas since an opposition offensive in mid-2012.

The push also comes a month after extremist militants of so-called Islamic State of Iraq and Levant (ISIL) terrorist group seized territories straddling Syria and neighboring Iraq where they have declared a self-styled caliphate. Most of the land was seized in June during a push across Iraq.

Rami Abdurrahman, who heads the Britain-based Syrian Observatory for Human Rights, said Monday that reinforcements, including members of the elite Republican Guards and allies from Lebanon's Hezbollah group, had recently arrived in Aleppo.

Abdurrahman and an activist based near the city who goes by the name of Abu al-Hassan said Monday's fighting was concentrated near an army base known as the Infantry Academy that militants captured two years ago.

The move against the rebel-held areas comes two months after hundreds of Syrian militants withdrew from parts of the central city of Homs that they had held for nearly two years despite a government blockade. Homs, once the center of the rebellion against President Bashar Assad, is currently under government control.

Syrian government forces last week seized the Sheikh Najjar neighborhood and a key industrial area, allowing them to choke off rebel-held parts of Aleppo.

A Syrian army officer told state TV that troops now control a main highway north of Aleppo and ``we have closed a belt of up to 80 percent from the north.''

A correspondent for the channel said that military experts were dismantling bombs placed by militants in the industrial area, adding that large amounts of weapons were captured.

NJF/NJF