Rebel forces took control of a strategic town in northern Syria on Monday, killing more than 50 pro-government fighters and cutting off government forces' only supply route out of the city of Aleppo, the Syrian Observatory for Human Rights said.
The Britain-based Observatory also said it had obtained a photograph showing the execution of Alawite cleric Badr Ghazal by hardline Islamist rebels, highlighting the growing sectarian bloodshed of the 2 and a half year conflict.
In Aleppo, rebels led by Islamist militant groups captured Khanasir, a town that sits on the government supply route connecting the northern province to the central city of Hama.
The rebel gain will leave government forces besieged in Aleppo province, according to the Observatory, which opposes President Bashar Assad's rule. The move hampers Assad's forces options for counterattack against the large swathes of rebel held territory in northern Syria along the Turkish border.
Rami Abdelrahman, head of the Observatory, told Reuters dozens of fighters from the paramilitary National Defence Forces (NDF) were killed. He said activists had so far counted 53 bodies, including that of the leader of the NDF's Aleppo-based forces.
The NDF is a volunteer force that likens itself to the army's reserve units. Its fighters generally stay in their own regions and have taken on the bulk of ground battles against the rebels, leaving Assad's more elite military forces to organize artillery and air strikes.
Further south, residents in the central province of Homs said rebels also tried on Monday to retake the strategic town of Talkalakh, 4 km (2.5 miles) from Lebanon's northern border. Its capture would allow rebels in the Homs countryside to replenish their supplies.
For weeks, Assad's forces had been on the offensive in Homs, a province they consider vital to securing their hold from Damascus to the president's coastal stronghold. The coast is home to a large number of Assad's Alawite minority sect, an offshoot of Shi'ite Islam, who mostly support the president.
But the advance near Talkalakh and the purported assassination of an Alawite cleric suggest the rebels are tentatively trying to push back in central Syria.
Sectarian violence has increasingly overtaken a conflict that began as peaceful protests against four decades of Assad family rule but has now become an all-out civil war.
Syria's Sunni Muslim majority has largely supported the uprising and Islamist groups among the rebels have increasingly threatened Alawites in retaliation for the killing of Sunnis.
The sectarian dimension of the conflict has drawn in foreign fighters from neighboring countries. Hundreds of Sunni militants have entered Syria to fight alongside the rebels.
Meanwhile, Lebanese Shi'ite militant group Hezbollah and Shi'ite militias from Iraq have sent men to fight alongside Assad's forces, angering Sunnis across the region.
Some Syrians were skeptical about the purported killing of the Alawite cleric Ghazal, saying there was still no definitive proof. It was not immediately possible to independently verify the report because of the restrictions imposed on foreign media.
Either way, the alleged killing or capture of Ghazal in Latakia province is a symbolic threat to Alawites on the coast, whose heavily fortified region has largely been spared the violence raging in most of the country.
The Observatory said rebels from the Nusra Front shot Ghazal after he was kidnapped by rebels in the northern suburbs of Latakia earlier this month. It was not clear when the execution might have occurred.
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