Jihadists and moderates in the opposition are increasingly turning on each other threatening a conflict within the rebel movement.
The Free Syrian Army has threatened retaliation over the killing
UK 13 Jul 2013 :: The assassination of a senior Free Syrian Army (FSA) commander by militants linked to al Qaeda is tantamount to a declaration of war, FSA rebels have said.
Kamal Hamami - better known as Abu Bassir al Jeblawi - of the FSA Supreme Military Council was killed by members of the Islamic State of Iraq and the Levant, a hardline Islamist group, on Thursday.
A senior FSA commander said the al Qaeda-linked militants had previously warned FSA rebels that there was "no place" for them in the northern Latakia province, where Hamami was killed.
He added that there would be retaliation for the killing.
"We are going to wipe the floor with them. We will not let them get away with it because they want to target us," he said on condition of anonymity
The statement is the latest sign of disarray in the armed opposition to Syrian President Bashar al Assad, who has regained the upper hand more than two years into an insurgency that grew out of Arab Spring-inspired pro-democracy protests.
Opposition sources said the killing of Mr Hamami followed a dispute over control of a strategic checkpoint in Latakia.
"FSA rebels fired into the air, and subsequently, an ISIS fighter shot Abu Bassir dead and wounded two other fighters from his battalion," the opposition Syrian Observatory For Human Rights said
The Observatory for Human Rights added that the FSA and the Islamic State have had violent exchanges in several areas of Syria over the past few weeks, showing growing antagonism between Assad's foes.
"Last Friday, the Islamic State killed an FSA rebel in Idlib province and cut his head off. There have been attacks in many provinces," the Observatory's Rami Abdelrahman said.
FSA Supreme Command Political Coordinator Louay Mekdad said Mr Hamami and his brother were shot dead at the roadblock by Abu Ayman al Baghdadi, the Islamic State's Emir of the coastal region.
He said a fighter who was travelling with them was set free to rely the message that the Supreme Command was now an al Qaeda target.
"If these people came to defend the Syrian revolution and not help the Assad regime, then they have to hand over the killers," Mr Mekdad said.
Syria's conflict turned violent in the face of a crackdown on protests. Civil war ensued with disparate rebel groups taking up arms and the Observatory says more than 100,000 people have been killed.
The FSA and the jihadists have sometimes joined forces on the battlefield but the divisions have been highlighted as the West considers arming the FSA and some Gulf states have funnelled weapons to the Islamists.
US congressional committees are holding up plans to arm the rebels because of fears that such deliveries will not be decisive and the arms might end up in the hands of Islamist militants.(Courtesy:Sky News)