Syrian government forces pushed deeper into a strategic rebel-held town near the Lebanese border, battling rebels in fierce street fighting, Syrian state media said Monday.

An activist group said at least 23 elite fighters from Lebanon’s Hezbollah militant group have been killed in the clashes, while Al-Arabiya news said at least 40 members were killed in the fighting.

The dead included a senior Hezbollah field commander, Fadi al-Jazzar, who spent time in Israeli jail, rebel sources in Syria reported Sunday night. Jazzar is believed to have served 14 years in jail in Israel for a border attack in 1991 before being released in a prisoner exchange.

The Britain-based Syrian Observatory for Human Rights, which tracks the country’s civil war, said that in addition to the deaths more than 100 Hezbollah members have been wounded in the fighting around the town of Qusair. If confirmed, it would be a blow to the Shiite group, which has come under harsh criticism in Lebanon for its involvement in Syria’s civil war.

Observatory director Rami Abdul-Rahman cited “sources close to the militant group” for the death toll but declined to reveal their identity. The Observatory relies on a wide network of activists in the ground in Syria.

For weeks, fighting has raged around Qusair, located in the central province of Homs. The regime launched a push Sunday to regain control of the town, which has been in rebel hands since early last year.

Before Sunday’s offensive, Qusair had been ringed by regime troops and Hezbollah fighters, an Assad ally, for several weeks.

The town lies along a land corridor between Damascus and the Mediterranean coast, the heartland of Assad’s Alawite sect, an offshoot of Shiite Islam. Many rebel fighters are Sunni Muslims and Qusair, overwhelmingly Sunni, had served as a conduit for shipments of weapons and supplies smuggled from Lebanon to the rebels.

Lebanese security officials confirmed at least four funerals were being held Monday morning for Hezbollah fighters killed in Syria. They spoke on condition of anonymity in line with military regulations.

In the mostly Shiite Lebanese border village of Qasr, located opposite Qusair, pillars of smoke could be seen billowing from the Syrian side of the border the crackle of gunfire along with the heavy thud of artillery and airstrikes forced residents to keep their children away from school.

Syria’s state news agency said President Bashar Assad’s troops took control of most of Qusair on Monday. But the state news service also said government forces are still fighting “terrorists” in several town districts.

The Syrian regime claims there is no civil war in the country but that the army is fighting foreign-backed terrorists trying to topple Assad’s government.

More than 70,000 people have been killed in Syria since March 2011.