Syrian regime battles for key rebel stronghold Syrian forces backed by Lebanon militant group Hizbollah pushed on Monday into the strategic city of Qusair, a key supply route for the opposition and a vital link for the regime between its coastal heartlands and Damascus. There were reports that as many as 23 Hizbollah militants and 56 rebel fighters were killed. If confirmed, the fatalities would represent the Lebanese group's largest losses in Syria as its involvement in its neighbour's conflict appears to deepen. An area in central Syria which borders Lebanon, Qusair has been of crucial importance to the rebels, giving them a transit route to Syria's third-biggest city of Homs. But the regime has been pushing to retake it as it sits on a strategic corridor linking the coastal areas with the capital. Hizbollah has said that it is only protecting Shia villages on the Syrian side of the border, which are threatened by Sunni militants. They say these rebels are foreign extremists. But rebels say that Hizbollah is playing a more offensive role and that its involvement has energised the regime's fightback. "They couldn't put [Qusair] under this siege until Hizbollah started supporting them," says one rebel fighter from a local battalion interviewed over Skype, who gives his name as Abu Assad. The regime is not well trained, and it's been fighting two years, it is an exhausted regime and exhausted army - Hizbollah have enthusiasm. Losing the city would deprive the rebels of their last significant foothold in central Syria, marking another setback in the battle for strategic arteries. The attempt to retake Qusair is the latest in a series of regime offensives in strategic parts of the country. The regime's recent successes reflect not only the help of Hizbollah but also an increased use of local militias, sometimes known as popular committees. These armed civilians are usually drawn from religious minorities, to whom the regime has delegated the defence of certain areas of the country. Abu Hamza, a member of a local committee working with the regime in Qusair, says his group has co-ordinated with the Syrian army to battle the rebels in the Qusair countryside, forcing the mainly Sunni rebels to pull back to Qusair city. "We were able to pull them [rebels] out," he says. The popular committee in Qusair appears also to be co-ordinating with Hizbollah, which arranged the interview with Abu Hamza. The regular flow of 4x4 vehicles with blackened number plates through the sleepy village of Al Qasr on the Lebanese side of the border is testament to the strong presence of Hizbollah. The Hizbollah death toll was reported by the UK-based Syrian Observatory for Human Rights on Monday, which also said that more than 70 were wounded in the attack on Qusair city. More than 70,000 people have been killed in Syria since the uprising began. While giving a greater role to allies and local militias may boost the regime's manpower, it has also changed the nature of the Syrian conflict, analysts say, risking greater Israeli involvement and a weaker state. Israel, which earlier this month launched air strikes near Damascus reportedly targeting a weapons cache bound for Hizbollah, is said to be concerned at the growing strategic co-operation between Iran, Hizbollah and the regime. The regime's increasingly overt collaboration with pro-government proxies also raises the possibility of multiple centres of power emerging within the pro-government ranks. The danger for the regime is that increased involvement of outside actors and local forces raises the regional stakes in the conflict and undermines its authority as a state. Analysts say this increasing use of local militias also runs the risk of fragmentation within the regime's own ranks. "The only way the regime can win, other than in the very narrow sense of survival in a devastated country, is by winning the battle for the state," says the International Crisis Group's Peter Harling. And we're seeing only further erosion on that level.