"Nusra's chief in Idlib (province), Yaacub al-Omar, was killed overnight when a bomb went off in his car near his house in the Khan al-Subul area," the so-called Syrian Observatory for Human Rights said on Saturday.

Two of his sons were wounded in the blast, the Britain-based group added.

Omar took over as local chief in April after his predecessor, Abu Mohammed al-Ansari, was killed by the so-called Islamic State of Iraq and the Levant terrorist group.

The two terrorist groups have been in conflict since the beginning of 2014.

The fighting between Nusra terrorists and other insurgents began in early July, with a particularly bloody battle breaking out in the Jisr al-Shugur region of Idlib a week ago.

Fighting there left scores dead on both sides, according to the Observatory.

RA/NJF