Regime forces advanced in northwestern Syria Friday as they pressed a deadly campaign against the last major opposition bastion in the country, a monitor said. The Syrian Observatory for Human Rights said government forces had taken hold of a stretch of a key highway in the jihadist-run region of Idlib. "Regime forces have seized the entire section of the Damascus-Aleppo highway that runs through Idlib province," Observatory chief Rami Abdel Rahman said. State media made no mention of control over that part of the highway, but said that government forces had taken control of two villages along the road. The M5 motorway has long been in the sights of the Damascus regime, as retaking it would allow traffic to flow from the capital to second city and former industrial hub Aleppo. The Observatory said the latest advance to the northeast of the crossroads town of Saraqeb meant pro-Damascus fighters only had a 30 kilometre (18 mile) stretch remaining to seize in Aleppo province to exert full control over the highway. Running up from the Jordanian border in the south of the country, the M5 is Syria's longest highway. It cuts through fertile fields, industrial zones and four major cities. The violence in Idlib since December has forced more than 580,000 people out of their homes, in one of the biggest upheavals in the nine-year civil war. More than 300 civilians have been killed in Idlib region in recent months, according to the Observatory. Syria's war has killed more than 380,000 people and displaced more than half the country's pre-war population since starting in 2011 with the brutal repression of anti-government protests. ah/dwo