Troops loyal to Syrian President Bashar al-Assad made new advances Sunday on the rebel stronghold town of Qusayr near the border with Lebanon, reports said.
Activists say the army, backed by pro-regime militia and the Lebanese Shiite movement Hezbollah, is aiming to crush insurgents in villages surrounding Qusayr, and to then launch an assault on the town itself.
Three new shells launched from the Qusayr area landed in eastern Lebanon, the official National News Agency reported, in what rebels described as retaliation for Hezbollah's involvement in Syria's war.
Two of the shells hit the outskirts of the town of Hermel and the other hit the Qasr area, said the Lebanese agency.
Qusayr has been under rebel control for more than a year.
"Loyalist troops backed by Hezbollah have taken control of important villages near Qusayr," said Rami Abdel Rahman of the Syrian Observatory for Human Rights.
Qusayr-based activist Hadi al-Abdallah told AFP that Hezbollah fighters were instrumental to the army's advance.
"The only reason why the regime is advancing in the Qusayr area is because of Hezbollah's troops. Hezbollah fighters advance on the ground, while the (Syrian) air force gives them cover," Abdallah said via the Internet.
Among the flashpoint villages were Radwaniyeh, seized on Saturday, Burhaniyeh and Tal al-Nabi Mando, which is strategic because it lies on a hilltop and overlooks rebel-held areas.
The army meanwhile secured the road linking the Lebanese-Syrian border along the Orontes river to the west of Qusayr.
The fighting has left dozens of people dead this week.
Meanwhile, pro-regime newspaper Al-Watan said "the army has control over villages near Qusayr".
"There is a big change in the army's tactics. It has become more precise in securing its objectives," the daily added.
According to Al-Watan, the rebels suffered another setback nearby.
"More than 100 of 500 terrorists who tried to storm the Dabaa airport were killed in an ambush set by the army, which is now chasing down the terrorists who fled," said Al-Watan, using the regime's term "terrorists" to refer to insurgents fighting the Assad regime.
The Observatory earlier this week reported rebels seized control of the Dabaa military airport, which has fallen out of use.