BEIRUT (AP) -- A car bomb exploded in eastern Syria near the border with Iraq on Tuesday, killing at least seven people, including a local rebel commander, opposition activists said.
The Britain-based Syrian Observatory for Human Rights said the blast struck near the offices of the al-Qaida-linked Nusra Front and another group, Ahrar al-Sham, in the village of Shmeitiyeh in Deir el-Zour province.
The Observatory, which relies on a network of activists on the ground, said an Ahrar al-Sham commander in the area and an Islamic judge affiliated with the Nusra Front also were among those killed.
There was no immediate claim of responsibility for the bombing.
Ahrar al-Sham and the Nusra Front have battled a rival faction, known as the Islamic State of Iraq and the Levant, in the oil-rich province since April in fighting that has killed more than 640 people and uprooted at least 130,000 civilians. The rebel infighting also has undermined the broader opposition battle against President Bashar Assad's forces, depriving the rebels of manpower and resources needed to fight the government.
The Islamic State holds sway over much of northern and eastern Syria, and is waging an offensive in Deir el-Zour against the government and rival rebels. The extremist group, which has been disavowed by al-Qaida, has also seized control of much of northern and western Iraq over the past week.
In a separate attack in Deir el-Zour, an Islamic State fighter detonated an explosive belt outside the home of a local rebel commander in the village of Huwayej, wounding him and killing two of his sons, the Observatory said. It added that there were also heavy clashes between the Islamic State and its rivals on the edge of the town of Basira.
Also Tuesday, the head of the international chemical weapons watchdog said that a preliminary report by the fact-finding mission sent to Syria to investigate alleged chlorine attacks "lends credence to the view that toxic chemicals" have indeed been used in the country.
Ahmet Uzumcu, the director-general of the Organization for the Prohibition of Chemical Weapons, said in a statement that the chemicals were "most likely pulmonary irritating agents, such as chlorine." The fact-finding team will continue to investigate, he said.
A separate, joint U.N.-OPCW mission is overseeing the destruction of Syria's chemical weapons program. That operation was created after a deadly chemical weapons attack on rebel-held areas near Damascus last August. The West blamed the attack on the Syrian government, which denied involvement.
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