BEIRUT - Rebels thrust into a strategic town in Syria's central Hama province on Thursday, activists said, pursuing a string of territorial gains to help cut army supply lines and cement a foothold in the capital Damascus to the south. They have made a series of advances across the country, seizing several military installations and more heavy weaponry, hardening the threat to President Bashar al-Assad's power base in Damascus 21 months into an uprising against his rule. Rebels said a day earlier they had captured at least six towns in Hama province. On Thursday heavy fighting erupted in Morek, a town on the highway that runs from Damascus north to Aleppo, Syria's largest city and another battleground. The opposition-linked Syrian Observatory for Human Rights said rebels were trying to take checkpoints in Morek, one of which they had already seized, and described the town as a critical position for the Syrian army. "The town of Morek lies on the Damascus-Aleppo road ... it has eight checkpoints and two security and military headquarters. If the rebels were able to control the town they would completely sever the supply lines between Hama and Damascus to Idlib province," the group said in an email. Idlib is in the rebel-dominated north bordering on Turkey.