By BARBARA SURK and ZEINA KARAM
Associated Press

BEIRUT (AP) - Fierce street fighting in a Syrian town near the Lebanese border has killed at least 28 elite members of Lebanon's militant Hezbollah group, activists said Monday, as Syrian government forces pushed deeper into the strategic, opposition-held town.

The Britain-based Syrian Observatory for Human Rights, which tracks Syria's civil war, said that more than 70 Hezbollah fighters have also been wounded in the fighting around the town of Qusair. If confirmed, the casualties would be a significant blow to the Iranian-backed Shiite group, which has come under harsh criticism at home for its involvement in the war next door.

A staunch ally of Syrian President Bashar Assad, Hezbollah is heavily invested in the survival of the Damascus regime and is known to have sent fighters to aid government forces. The Lebanese group's growing role in the conflict also points to the deeply sectarian nature of the war in Syria, in which a rebellion driven by the country's Sunni majority seeks to overthrow a regime dominated by the president's Alawite sect, an offshoot of Shiite Islam.

The increasingly overt Hezbollah involvement in the Syrian conflict is almost certain to threaten stability in Lebanon, which is sharply split along sectarian lines, and between supporters and opponents of Assad.

The Observatory, which relies on a wide network of activists on the ground in Syria, cited "sources close to the militant group" for the death toll but declined to reveal their identity. It said at least 50 Syrian rebels were also killed in the battle for Qusair on Sunday, including two commanders.

Qusair has been the target of a withering government offensive in recent weeks, and the countryside around the town has been engulfed in fighting as regime troops backed by Hezbollah fighters seized villages while closing in on Qusair itself. The opposition estimates that some 40,000 civilians are currently in the town.

The intensity of the fighting reflects the importance that both sides attach to the area. In the regime's calculations, Qusair lies along a strategic land corridor linking Damascus with the Mediterranean coast, the Alawite heartland. For the rebels, overwhelmingly Sunni Qusair has served as a conduit for shipments of weapons and supplies smuggled from Lebanon to opposition fighters inside Syria.

Regime troops and Hezbollah fighters, who laid siege to Qusair weeks ago, launched an offensive to regain control of the town, with Hezbollah's elite fighters advancing from the east and south, an opposition figure said.

He added that it took Hezbollah troops a few hours to take control of the town's main square and municipal building. By the end of the day Sunday, they had pushed out rebel units, including the al-Qaida-affiliated Jabhat al-Nusra, from most of Qusair, he said on Monday, speaking on condition of anonymity for fear of retaliation by both sides.

He said fighting was focused in the northern part of the town on Monday.

The account matched that of Syria's state news media, which said President Bashar Assad's troops took control of most of Qusair on Monday. State-run TV said forces restored stability to the entire eastern front of the town, killing scores of "terrorists" there _ the term used by the Syrian regime to refer to all rebels.

An official in the Homs governor's office told the AP on Monday that more than 60 percent of the city is in government hands after scores of gunmen were killed or surrendered Sunday. The official, who spoke on condition of anonymity because he was not allowed to give information to the media during an ongoing military operation, said more than 1,500 residents fled the city due to intensified fighting.

Qusair-based opposition activist Hadi Abdullah denied official reports that the army was advancing in the town, saying they were still trying to storm it.

"They go in and out, until now I can say with confidence that they have not been able to enter the town and stay there," Abdullah said.

Hezbollah members have made use of their expertise in guerrilla tactics to significantly boost regime forces in the fight for Qusair. Their presence, along with that of Hezbollah-backed Shiite fighters, is meant to shore up overstretched government troops fighting on several other fronts.

Residents on the Lebanese side of the border just across from Qusair reported seeing more than 30 plumes of smoke billowing from inside Syria and hearing the heavy thud of artillery and airstrikes late into the night Sunday and on Monday morning.

"Nobody could sleep last night from the sounds of battle," said Ali Jaafar, deputy mayor of the Lebanese border town of Hermel, adding that residents did not send children to school Monday for fear of fighting spilling over into Lebanon.