The Hezbollah terrorist group on Monday buried a leading commander in southern Lebanon, after he was killed "performing his jihadist duties in Syria", as the group put it.

"The Islamic Resistance (armed wing) is celebrating a leader from its heroic, sacrificing forces, the martyr Hassan Hussein al-Hajj... who died while performing his jihadist duties in Syria," Hezbollah said in an official obituary quoted by AFP.

Hezbollah has intervened in Syria on behalf of the embattled regime of President Bashar Al-Assad, dispatching fighters and commanders to various fronts around the country.

Hezbollah leader Hassan Nasrallah has promised that his group will be wherever is needed in Syria and has also declared he was willing to go fight in Syria himself.

According to the South Lebanon local news website, which is close to Hezbollah, Hajj was "the head of Hezbollah's operations inside Idlib" in northwest Syria.

He was killed in fierce clashes between Hezbollah fighters and "a takfiri (extremist Sunni) group", it said, according to AFP.

Although Hezbollah did not specify when Hajj was killed, local news websites in Lebanon said he died on Saturday.

Phillip Smyth, an expert on Shiite militias in Syria and Iraq, told AFP that Hajj was a "leading command element" in Hezbollah and killed in Idlib.

The group's Al-Manar television broadcast live coverage of Hajj's funeral procession to Al-Louaizeh village, where his burial was attended by large crowds including Hezbollah officials.

It was a rare move for the group, which has normally refrained from giving details on its military losses in Syria, though it has been documented that the group has suffered “heavy losses” in the country.

Hezbollah's obituary said Hajj had led "some of the most famous special operations" against Israeli forces.