Nearly 150 Syrian soldiers have been besieged inside a hospital in Jisr al-Shughur since opposition forces including an Al-Qaeda affiliate seized the town last week, a monitor said Thursday.
The Syrian Observatory for Human Rights said that separately another 200 people -- regime forces and their families, captured from Jisr al-Shughur and its surroundings in the northwestern province of Idlib -- were being held hostage.
Earlier this week, the Syrian government said a "massacre" of some 200 civilians had taken place in the region of Jisr al-Shughur, which fell Saturday to a coalition of Al-Qaeda affiliate Al-Nusra Front and other opposition groups.
"Nearly 150 soldiers and some civilians are besieged inside a hospital building and there were violent clashes on Thursday between them and rebels" outside the building, Observatory director Rami Abdel Rahman said.
Syria's Al-Watan newspaper, which is close to the government, appeared to make reference to the same group on Thursday, saying "soldiers were engaged in heavy fighting" against "thousands of terrorists" in the vicinity of the hospital.
The Observatory said Al-Nusra and other rebel groups in control of Jisr al-Shughur had tried to take the building in an unsuccessful attack on Wednesday.
Separately, the monitor said, some 200 people were being held by Al-Nusra and allied forces.
The Observatory said they had been taken hostage from Jisr al-Shughur and the nearby Ishtabraq area during the battle for the town.
On Monday, the foreign ministry sent a letter to the United Nations alleging that "terrorists have massacred nearly 200 civilians, the majority of them women and children, in Ishtabraq."
It alleged the bodies of those killed had been left in fields in the area.
Ishtabraq is majority Alawite, the Shiite offshoot sect to which President Bashar al-Assad belongs.
Regime forces have lost most of Idlib province in recent weeks, with a coalition of opposition forces calling themselves the Army of Conquest seizing first the provincial capital of the same name, then Jisr al-Shughur and a military base.
Government forces now retain only a few military bases and smaller towns in the province, which borders Turkey.
Elsewhere, Syrian state news agency SANA said at least seven people were killed and 35 injured in opposition fire on government-held parts of Aleppo city.
Once the country's economic powerhouse, Aleppo city has been divided between government control in the west and rebel control in the east since shortly after fighting began there in mid-2012.
Government planes regularly bombard the rebel side from the air while opposition forces launch rockets at regime-held areas.