BEIRUT (AFP) - Nearly 1,400 people have been killed in Syria since clashes between rebels and the jihadist Islamic State of Iraq and the Levant (ISIL) erupted this month, a monitor said on Thursday.

"The number of people killed in fighting between the Islamic State of Iraq and the Levant and Islamist and rebel forces since January 3 has risen to 1,395," the Syrian Observatory for Human Rights said.

The Observatory, a Britain-based group that relies on activists and other sources on the ground, said the figure included 760 moderate and Islamist rebels, 426 ISIL fighters, 190 civilians and 19 others whose identities have not been established.

Clashes between rebels and jihadists from ISIL erupted early in January after months of rising tensions.

The all-out fight has seen ISIL lose territory in Idlib and Aleppo provinces, but it has consolidated its hold over Raqa city, the only provincial capital to be pried from regime control.

Elsewhere in northern Syria, near the Turkish border, ISIL militants seized control of Manjib, northeast of Aleppo, after several days of clashes in which 12 Kurdish fighters died, the Observatory said.

And three people were killed, including a young girl, and 15 wounded in a car-bomb blast in the Kurdish-held village of Malkiyeh close to the border.

Regime air raids on Aleppo left another 16 people dead, including three women and eight children, after warplanes hit several rebel-held areas in the south of the city.

Al-Qaeda leader Ayman al-Zawahiri, in an audio message posted online on Thursday, urged all jihadist forces "to immediately halt fighting between brothers". While opposition fighters initially welcomed foreign jihadists to the battle, ISIL has been accused of a string of abuses against civilians and rival rebel groups.

Among the abuses that sparked the fierce clashes was ISIL's kidnap, torture and execution of a doctor from a powerful Islamist rebel brigade.