Local al-Qaeda leader latest opposition figure assassinated in Syria

A local leader of al-Qaeda's Syrian affiliate was assassinated by unknown gunmen on Wednesday, the latest in a string of killings of hardline rebels, a monitor said.

The Syrian Observatory for Human Rights said Iyad al-Adl, "emir" for the town of Ariha in northwestern Syria's Idlib province, was shot dead along with a second member of al-Nusra Front.

The Britain-based monitor said unidentified gunmen opened fire on the car in which the men were driving in a western neighbourhood of Ariha.

The assassination is the latest in a series of targeted killings over the past few weeks of senior rebels, including from the al-Qaeda affiliate Nusra and its ally Ahrar al-Sham.

Earlier this month, Abu Rateb al-Homsi, a leader of Ahrar al-Sham in Homs province, was shot in the head while he drove through a village with his wife.

His death came just weeks after the killing of Zahran Alloush, leader of the rebel group Jaish al-Islam, in an air strike claimed by the Syrian government.

Analysts say the killings could be the work of the government or the Islamic State group, which considers all factions that have not pledged allegiance to it to be its rivals.

At least 20 rebel commanders have been killed in the assassinations since early December in several parts of Syria, including central Homs province, southern Daraa and elsewhere in Idlib.

Idlib province is held by the powerful "Army of Conquest" coalition of rebels including Nusra and Ahrar al-Sham.

Rebel groups have regularly accused IS of having sleeper cells in their territory, but the militant group has not openly claimed the assassinations.

More than 260,000 people have been killed in Syria since the conflict began in March 2011 with anti-government protests.