Hezbollah chief Naim Qassem said Thursday that his Lebanese militant group, an ally of Syrian President Bashar Assad, would be by Damascus’s side as Islamist-led militants press a sweeping offensive.

In a televised address, Qassem denounced “terrorist groups” who want to “destroy Syria again... to bring down the government” and “create chaos.”

“They will not be able to achieve their goals despite what they have done in past days, and we as Hezbollah will be by Syria’s side in thwarting the goals of this aggression as much as we can,” Qassem said.

He did not elaborate on what sort of support his group might provide, but Hezbollah suffered heavy losses in its war with Israel which ended with a fragile ceasefire on November 27, the day the Syria militants launched their offensive.

Qassem accused the United States and Israel of supporting “takfiri” factions, a term the Shiite Muslim group uses to refer to jihadists or supporters of radical Sunni Islam.

Militant group Hayat Tahrir Al-Sham (HTS), led by Al-Qaeda’s former Syria branch, and allied factions launched the surprise attack and have since seized the major cities of Aleppo and Hama.

The militants’ advance in Aleppo province was in an area where pro-Iran groups including Hezbollah had previously had a significant presence, before drawing it down in recent months in the face of the war with Israel.

Hezbollah has openly backed Assad’s forces since 2013.

Hezbollah fighters helped Assad regain territory lost earlier in the civil war which broke out in 2011 after the repression of anti-government protests.

In his speech, Qassem also announced that his group and its backer Iran had allocated $77 million so far to Lebanese displaced by its war with Israel, with more to come.

"In November, Hezbollah decided to give a monetary gift -- a gift from the Iranian people and Hezbollah -- of between $300 and $400 for each family," out of more than 233,000 families who registered for its assistance, Qassem said.

"A total of $57 million has been paid," covering 172,000 families, or some 75 percent of those registered, while the rest will receive a total of $20 million, he added.

Qassem thanked Iran for "the generous support", emphasising Hezbollah's commitment to shelter and reconstruction.