BEIRUT — Syrian rebels said Friday the assassination of one of their top commanders by Al-Qaeda-linked militants was tantamount to a declaration of war, opening a new front for the fighters struggling against President Bashar Al-Assad's forces. Rivalries have been growing between the Free Syrian Army (FSA) and the militants, whose smaller but more effective forces control most of the rebel-held parts of northern Syria more than two years after pro-democracy protests became an uprising. “We will not let them get away with it because they want to target us,” a senior FSA commander said on condition of anonymity after members of the Islamic State of Iraq and Levant killed Kamal Hamami Thursday. “We are going to wipe the floor with them,” he said. Hamami, also known by his nom de guerre, Abu Bassir Al-Ladkani, is one of the top 30 figures on the FSA's Supreme Military Command. The FSA commander said the Al-Qaeda-linked militants had warned FSA rebels that there was “no place” for them where Hamami was killed in Latakia province, a northern rural region of Syria bordering Turkey where militant groups are powerful. Other opposition sources said the killing followed a dispute between Hamami's forces and the Islamic State over control of a strategic checkpoint in Latakia and would lead to fighting. The two sides have previously fought together from time to time, but the FSA, desperate for greater firepower, has recently tried to distance itself to allay US fears any arms it might supply could reach Al-Qaeda. Louay Mekdad, FSA Supreme Command Political Coordinator, said Abu Ayman Al-Baghdadi, the Islamic State's Emir of the coastal region, personally shot dead Hamami and his brother at the roadblock. He said a fighter who was traveling with them was set free to rely the message that the Islamic State considers the FSA heretics and that the Supreme Command is 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,” Mekdad said, adding that the bodies of the two men were still with the Al-Qaeda affiliate. The FSA has been trying to build a logistics network and reinforce its presence across Syria as the US administration considers sending weapons, in part to present a bulwark against units it considers “terrorist organizations.” The anti-Assad Syrian Observatory for Human Rights, which monitors the conflict, said 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 leader Rami Abdelrahman said. — Reuters