'IS car bombs' in Syria's Aleppo kill 32

The toll from two alleged Islamic State (IS) group car bombings overnight of rebels in Syria's Aleppo province has risen to at least 32 people, a monitor said on Wednesday.

Three local commanders were killed in one of the attacks, the Syrian Observatory for Human Rights said, describing the incidents as an apparent IS attempt to expand in the northern province.

One bomb hit a base in the village of Hawar Kilis, near the Turkish border, killing at least 23 rebels, the Britain-based Observatory said.

The second targeted a joint rebel office in the town of Marea and killed nine, including the three commanders.

An earlier report gave an overall toll of 27.

The Observatory said the commanders were from the conservative Jabhat Shamiya and Jaish al-Mujahideen groups and the al-Nusra Front, al-Qaeda's local affiliate, which confirmed the death of its commander on its official Twitter accounts.

"Abu Maria, al-Nusra Front's emir (leader) in Marea, northern Aleppo, was martyred after being targeted by a car bomb by the (Islamic) State group," al-Nusra said.

The group also posted a picture of what appeared to be the man’s body wrapped in a blanket.

The Observatory said clashes erupted between rebels from local groups and IS fighters in and around Marea after the attack there, though they had subsided by Wednesday morning.

Observatory director Rami Abdel Rahman said the attacks appeared to be a bid by IS to "expand their reach" in Aleppo province, where the group already has considerable power.

Marea and Hawar Kilis are both under the control of groups opposed to IS.

Despite sharing a similar ideology, al-Nusra and IS are at odds in fronts across most of Syria, and while rebel groups have battled IS, they cooperate with al-Nusra in many places.

Marea and Hawar Kilis lie north of the provincial capital, Aleppo city, the country's one-time economic powerhouse, which has been devastated by the civil war.

Aleppo has been highly contested territory throughout the Syrian civil war, with a number of militant groups fighting for control of the city. The Syrian military has been criticised for its use of barrel bombs in the highly populated area. Human Rights Watch said in a damning report last year that the barrel bombs “terrorize” the people of Aleppo.

More than 215,000 people have been killed in Syria since the conflict began in March 2011 with anti-government protests, which spiralled into war after a government crackdown.