Syria civil war: President Assad's army regains control of strategic Lebanon border town of Qusair from rebels

The town had been the scene of weeks of fighting

Syrian citizens inspect the site of an air strike in Qusair last month (AP)

Syrian government forces have claimed victory in the battle for the strategic town of Qusair in the country's long civil war.

The town, close to the Lebanese border, has been the scene of nearly three weeks of fighting, and of the first open involvement from Lebanon's Hezbollah militants in the war. It lies along a land corridor linking two of President Bashar al-Assad's stongholds - Damascus and an area along the Mediterranean coast that is the heartland of his minority Alawite sect.

For the rebels, who had been in control of the town since the uprising against Assad began, holding Qusair meant protecting their supply line to Lebanon, just 10 km away. A wide pro-Assad offensive on Qusair was launched on May 19.

Its capture solidifies some of the regime's recent gains on the ground that have shifted the balance of power in Assad's favour.

State TV said the army "restored security and peace" after successfully dismantling "terrorist networks" operating in the town over the last few days. An official in the governor's office of Homs province confirmed the report.

"At 6.30 am, Qusair became secure," the official said, and the official Syrian news agency SANA said some of the rebel fighters have surrendered.

It comes just a day after France and Britain made back-to-back announcements that the nerve gas sarin was used in Syria's conflict. A UN probe, also released Tuesday, said it had "reasonable grounds" to suspect small-scale use of toxic chemicals in at least four attacks in March and April in Syria.

Syria's civil war, now in its third year, is thought to have killed more than 70,000 and displaced more than one million. It is fought between forces loyal to President Assad and rebels, mostly from the disparate Free Syrian Army.

The conflict has spilled periodically across Syria's borders with Lebanon, Iraq and Turkey, threatening to engulf the region.

In the past week, rebels in Qusair called on fighters from all over Syria to come to their aid, and foreign fighters were suspected to be playing a large role in the city's defence.

The battle has also laid bare Hezbollah's growing role in the Syrian conflict. The Shia militant group, which has been fighting alongside Assad's troops, initially tried to play down its involvement, but could no longer do so after dozens of its fighters were killed in Qusair and buried in large funerals in Lebanon.

Hezbollah's leader, Hassan Nasrallah, firmly linked his militant group's fate to the survival of the Syrian regime, which has been one of its strongest allies.

Lebanon's Al-Mayadeen TV, which has reporters embedded with Syrian troops, was reporting live from Qusair today, showing images of damaged buildings and a deserted town. The reporter said there was no sign of fighting.

The municipal building in the centre of Qusair appeared to be pockmarked from fighting. A Syrian flag was raised above it, claiming government control of the town.