Islamic State fighters have captured two key towns and several villages near Syria's northern border with Turkey after pushing out rival fighters in fierce clashes, opposition groups and activists said.
Activists said fighters from the group captured the towns of Akhtarin and Turkmanbareh after fierce clashes with rebels who are fighting to topple Syrian President Bashar al-Assad.
The IS fighters also took a string of nearby villages over which they had been fighting, including Masoudiyeh, Dabiq and Ghouz.
The Britain-based Syrian Observatory for Human Rights said at least 31 rebels and eight Islamic State group fighters were killed in the clashes. The Observatory relies on a network of activists inside Syria for its information.
The capture of Akhtarin has strategic significance as the town is "the gate to the northern countryside of Aleppo," said a local rebel commander who goes by the name Abu Thabet.
It seems the Islamic State group's ultimate goal, he said, was to reach Marea, a town a few kilometers to the west that is considered a stronghold of the Islamic Front as well as Azaz, a town located next to the Bab al-Salama border crossing with Syria.
The Islamic Front is a alliance of rebel groups battling against the Islamic State group.
"They launched an all-out offensive for Akhtarin on Tuesday and the clashes lasted all night," said Abu Thabet, whose Aleppo Swords brigade is affiliated with the Western-backed Free Syrian Army (FSA) umbrella group.
He said rebels, including the FSA, were in chaos - encircled in Aleppo province by Syrian government forces on one side and the Islamic State group on the other side.
The fighters from the al-Qaeda breakaway Islamic State group control huge swaths of territory in eastern and northern Syria and are fighting rival rebels, Kurdish fighters and the Syrian army for more. In neighboring Iraq they are batting Iraqi Kurdish peshmerga fighters as well as Iraqi government troops.
The takeover of Akhtarin and surrounding Syrian villages was also reported on social media by fighters affiliated with the Islamic State group.
Sarin gas destruction completed
Also on Wednesday, the international chemical weapons watchdog said all 581 metric tons of Syria's precursor chemicals for sarin gas that had been transferred to the US cargo vessel MV Cape Ray have been destroyed.
The Organization for the Prohibition of Chemical Weapons said the Cape Ray has now begun to neutralize the remaining Syrian chemicals on the ship - 19.8 metric tons of sulfur mustard.
The remaining 700 metric tons of chemicals removed from Syria as part of a joint OPCW-UN mission are being destroyed at land-based facilities in Finland, the UK and the US
The operation began after Syria agreed to relinquish its chemical weapons programme in the wake of a deadly chemical attack outside Damascus a year ago.