BEIRUT (AP) -- Islamic extremists captured two key towns and several villages near Syria's northern border with Turkey on Wednesday after pushing out rival fighters in fierce clashes, opposition groups and activists said.
The towns, located in Syria's Aleppo province, are the latest prize for Islamic State militants who have carved out a self-styled caliphate across vast swaths of eastern Syria and northern and western Iraq.
Activists said fighters from the group captured the towns of Akhtarin and Turkmanbareh after fierce clashes with mainstream rebels who are fighting to topple Syrian President Bashar Assad. The militants 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 uses the nom de guerre Abu Thabet.
It seems the Islamic State's ultimate goal, he said, was to reach Marea, a town a few kilometers (miles) 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 Turkey.
The Islamic Front is a powerful 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 moderate Aleppo Swords brigade is affiliated with the Western-backed Free Syrian Army umbrella group.
He said the mainstream 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-Qaida breakaway Islamic State group control huge swaths of territory in eastern and northern Syria and are fighting rival rebels, Kurdish militias 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 jihadists affiliated with the Islamic State group.
Also Wednesday, the international chemical weapons watchdog said all 581 metric tons (640 tons) of Syria's precursor chemicals for sarin gas that had been transferred to the U.S. 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 (22 tons) of sulfur mustard.
The remaining 700 metric tons (772 tons) of chemicals removed from Syria as part of a joint OPCW-U.N. mission are being destroyed at land-based facilities in Finland, the United Kingdom and the U.S.
The operation began after Syria agreed to relinquish its chemical weapons program in the wake of a deadly chemical attack outside Damascus a year ago.
Syria's conflict began in March 2011 as a popular uprising against Assad's rule, but turned into an insurgency after government forces violently cracked down on demonstrators. It has since deteriorated into a civil war with sectarian overtones and increasingly powerful Islamic militant groups. Over 170,000 people have been killed in Syria in over three years of fighting, activists say.
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