Syrian rebels were engaged in fierce battles Thursday with regime forces trying to capture the town of Yabrud, their last stronghold in the strategic Qalamun region near the Lebanese border, an NGO said.
Meanwhile, in the northern city of Aleppo, eight soldiers were killed by a rebel suicide bombing at the city's central prison, which rebels have long been trying to capture, the Syrian Observatory for Human Rights said.
And 18 rebel fighters were killed when they launched a dawn assault against an Alawite village in central Homs province.
The Observatory said rebels were fighting on Yabrud's outskirts against government troops, backed by National Defence Forces militia and Lebanon's Shiite movement Hezbollah.
The rebel side included Islamist brigades and Al-Nusra Front, an Al-Qaeda affiliate, the Britain-based Observatory said.
"There have been many losses on both sides, but there are not exact figures yet," the Observatory said, adding that a citizen journalist with the rebels was among those killed.
A source close to Hezbollah said the government would seize Yabrud soon.
"Yabrud will be take by the Syrian army very soon, by force or through negotiations. Then the mountain leading to the village of Arsal (in Lebanon) will be taken."
Syria's Al-Watan newspaper said the "army is advancing around the town and is ready to take control," with a security source telling AFP the plan was to advance incrementally on all sides of the town "until it is taken completely."
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The battle is crucial for Hezbollah, which says most of the vehicles used in recent car bombing of its strongholds in Lebanon have come from Yabrud, which lies just over the border.
Yabrud was once home to some 30,000 residents, around 90 percent Sunni Muslim and 10 percent Christian.
It has been a rebel stronghold since early in the uprising that began in March 2011, and is now the only key town remaining under opposition control in the Qalamun region after a regime advance last year.
In central Homs, the Observatory said 18 rebels were killed after launching a dawn raid on Al-Qumeiri, an Alawite village.
Troops and members of the National Defence Forces militia pushed the rebels back, the group said.
In Aleppo, meanwhile, the Observatory said eight soldiers were killed and 20 wounded in a triple suicide bombing by Al-Nusra Front.
The Observatory group said a car exploded at the entrance to the prison and two suicide bombers blew themselves up inside the facility, after which Syrian army aircraft began bombing the area around the prison.
For months, rebels have launched attacks on the prison, which reportedly holds some 3,000 detainees, including Islamists, activists and minors.
At the beginning of February, they took over much of the facility in their biggest assault yet, but were driven out by government troops the following day.
Meanwhile, in southern Daraa, two children and a teenager were killed in air raids and shelling on the village of Jassim.