The head of Lebanon's Hezbollah movement said Friday that the offensive on the city of Aleppo was the "greatest battle" in Syria, pledging to dispatch more fighters to support Syrian regime forces.

In remarks broadcast on the Shiite group's Al-Manar television, Hassan Nasrallah said his party would "increase our presence in Aleppo... because the real, strategic, greatest battle is in Aleppo and the surrounding area."

He spoke at a commemoration event for Mustafa Badreddine, a Hezbollah commander killed in an explosion on May 12 near Damascus international airport.

Hezbollah has intervened in Syria's complex war on behalf of the regime of President Bashar al-Assad and has dispatched thousands of fighters to Damascus, Aleppo, and Homs provinces, among others.

Aleppo city -- once Syria's economic hub -- in particular has seen an uptick in violence over the past two months between government forces in the west and rebel groups in the east.

Regime fighters, backed by Hezbollah and government and Russian warplanes, are seeking to close off the last rebel route out of the city.

"We are facing a new wave, or a new phase, of military operations in Syria that will be fought in the north, specifically in the area of Aleppo," Nasrallah said.

He announced that 26 Hezbollah fighters had been killed in the offensive this month, a rare admission of casualties for the group.

According to the Syrian Observatory for Human Rights, which monitors the war-torn country and tallies casualties, at least 25 Hezbollah fighters have been killed in fighting south of Aleppo city.

"Fighting in defence of Aleppo is in defence of the rest of Syria, of Damascus. It's in defence of Lebanon and Iraq and Jordan," Nasrallah said via video-link.

"This is why it is our duty to be in Aleppo -- and we were, and we will stay in Aleppo."

More than 280,000 people have been killed since Syria's war erupted in 2011, and millions have been forced to flee their homes.

International efforts to reach a political solution to the war have faltered and a ceasefire brokered by the US and Russia has all but collapsed.

In Aleppo, several temporary freezes on fighting have been announced in an attempt to bolster the broader truce but violence has steadily risen.

Nasrallah accused the United States of securing the truce in Aleppo to give rebels a change to re-arm.

"Who benefitted from this truce? Those who brought thousands of fighters, artillery, ammunition, to revive their offensive (on Aleppo)," he said.

Source: AAFP