The Damascus regime has "wilfully" killed thousands of civilians in air strikes that amount to war crimes, Human Rights Watch said on Thursday, as rebels lobbied the major powers for weapons. G8 foreign ministers gathered for a second day of talks in London after several of them met opposition leaders to discuss their calls for arms to tilt the balance in their fight to oust President Bashar al-Assad.

Rebels fighting to oust Syrian President Bashar al-Assad's regime on Monday sealed off the country's only two border posts with Jordan, a military official said. "The Free Syrian Army closed the two crossings of Daraa and Naseeb from their side after they took control of them," the Jordanian official told AFP on condition of anonymity. He declined to elaborate. The development comes after the rebels seized a 25-kilometre (15-mile) strip of land stretching from the Jordanian border to the Israeli-occupied Golan Heights, according to the Syrian Observatory for Human Rights.

Riad Asaad, commander of the rebel Free Syrian Army, was injured overnight in a blast that hit his car in eastern Syria, the Syrian Observatory for Human Rights watchdog said on Monday. "An explosive device exploded last night near the car carrying Free Syrian Army commander Riad Asaad, who was conducting a tour of the town of Mayadeen in Deir Ezzor province," Observatory director Rami Abdel Rahman told AFP.

Syria's government on Tuesday accused rebel forces of using chemical weapons for the first time, but the opposition denied the claim, saying instead that government forces might have used banned weapons. "Terrorists fired rockets containing chemical materials on Khan al-Assal in Aleppo province," the state news agency SANA and Syrian state television said. Syria's Information Minister Omran al-Zohbi called the attack a "dangerous escalation," saying that 16 people were killed and 86 injured in the incident.