DAMASCUS - Syria's northwest region of Al-Haffe has been "cleansed" of terrorists and "calm has been restored" in the area, the official SANA news agency quoted officials as saying on Wednesday.

"Security and calm were restored in the area of Al-Haffe (in Latakia province), which was cleansed after armed terrorist groups assaulted citizens and vandalised and burned a number of public and private properties," the agency said.

"The authorities pursued the remaining terrorists in the villages surrounding Al-Haffe" where they "killed and arrested a number of them", SANA said, adding that government forces also sustained casualties in the clashes.

Authorities reported that large quantities of weapons were confiscated from the "terrorists" including "missiles ... sniper rifles, machine guns, improvised explosive devices, mortar launchers, RPGs and large amounts of ammunition."

Syrian rebels withdrew on Wednesday from the besieged town of Al-Haffe and nearby villages that had been under intense shelling by regime forces for eight days, according to the Syrian Observatory for Human Rights.

"The town and villages of Al-Haffe were subjected to aerial, tank and rocket bombardment, as well as a suffocating siege by regime forces and thugs," the rebel Free Syrian Army said, adding that its fighters retreated "to avoid falling into the regime's civil war trap."

"The rebels withdrew from Al-Haffe and the entire region at dawn in order to spare the lives of residents undergoing extremely violent shelling," said Observatory head Rami Abdel Rahman.

In a statement, the rebel FSA's Military Council described the retreat as a tactical move "to avoid a massacre by regime forces of Al-Haffe's remaining residents."

The rebels also evacuated "the injured, the martyrs, women and children" from the area, it said.

Describing the area as "a disaster zone," the rebels vowed to continue fighting.

Latakia-based activist Abu Mohammad on Wednesday reported that "regime forces and shabiha (pro-regime militiamen) raided Al-Haffe and the surrounding villages" after the rebels withdrew.

"The shabiha immediately started to loot and steal," he said via Skype, adding that he feared regime forces might kill any remaining residents, as reportedly happened in other areas of Syria following the withdrawal of rebel fighters.

"The snipers are everywhere," Abu Mohammad said.

The United Nations and opposition activists had previously expressed fears of a massacre in Al-Haffe, if pro-government forces entered the majority Sunni Muslim town, just 16 kilometres (10 miles) from President Bashar al-Assad's mainly Alawi hometown Qardaha.

Three people were killed and dozens wounded in clashes in Al-Haffe on Tuesday, the Observatory said.

UN observers came under fire in a village near Al-Haffe on Tuesday after government supporters surrounded their vehicles as they were trying to reach the besieged town, a UN official said.