Aleppo is 'the greatest battle' in Syria, says Nasrallah

He vowed to dispatch more fighters in the ancient city to boost support for Russian-backed Syrian regime forces on the ground.

Hizballah will "increase our presence in Aleppo... because the real, strategic, greatest battle is in Aleppo and the surrounding area," he said in remarks broadcast on al-Manar television to mark a commemoration event for Mustafa Badreddine, a commander killed in an explosion in Syria in May.

Lebanon's Hizballah blamed Islamist extremists for killing the group's top military commander in an artillery attack on May 12, vowing to avenge his death by continuing its involvement in Syria’s civil war.

Badreddine was on a US terror sanctions blacklist and was a key suspect in the 2005 assassination of Lebanese ex-premier Rafik Hariri in Beirut. He was also one of the "most wanted" men by Israel.

His predecessor, cousin and brother-in-law Imad Mughniyeh, was killed in Damascus in a 2008 bombing that Hizballah blamed on its regional arch-foe Israel with whom it has fought several wars.

Badreddine's assassination follows the killing of Samir al-Kuntar, another Hizballah commander and former detainee in Israel five months ago. Israel was widely viewed as the culprit.

Meanwhile, the UN envoy to Syria, Staffan de Mistura said earlier this week that he hope peace talks can resume in July of the humanitarian and security situation improves on the ground.

The UN-backed talks aim to reach a political settlement to Syria's brutal five-year war, but the process has deadlocked while on the ground a fragile truce hangs by a thread.

"The window of opportunity is coming quickly to a close unless we maintain alive the cessation of hostilities, we increase humanitarian aid and we come to some common understanding of a political transition," de Mistura told the UN General Assembly via video link from Geneva.