Syrian activists and an official with an ultraconservative rebel group say gunmen have shot and killed the group's commander the main central province.

Labib al-Nahhas of Syria's Ahrar al-Sham Islamic rebel group mourned on his Twitter account late on Tuesday the death of Abu Rateb al-Homsy, the group's leader in Homs province. It was not clear when al-Homsy was killed.

The Britain-based Syrian Observatory for Human Rights says al-Homsy was shot while in a car with his wife in the village of Farhaniyeh. She was wounded in the attack.

Several local commanders of insurgent groups have been assassinated over the past weeks in Homs. No one has claimed responsibility for the killings.

Ahrar al-Sham is one of the most powerful rebel groups and is active in different parts of Syria.