Syrian forces assisted by Hezbollah militants have captured the town of Qusayr after an 18-day battle.

The strategic town, close to the border with Lebanon, had been under rebel control for months.

Hezbollah is thought to have led the attack and fighters from the group are being used more and more by government forces in Syria.

Iran congratulated Syria on the victory.

Meanwhile US President Barack Obama says a "high level of proof" is needed that chemical weapons have been used by Al Assad, something which he previously warned would be crossing a "red line."

The French Foreign minister says samples from Syria have been sent for further analysis to determine whether or not sarin gas was used against rebel fighters.