Syria's protest flashpoint town of Banias was completely cut off from the outside world on Tuesday, still encircled by the army three days after a residential neighbourhood was strafed by deadly gunfire.

"Security forces and the army continue to assault Banias and we know what they are preparing for us," said Anas al-Shuhri, one of the leaders of the opposition movement challenging the regime of President Bashar al-Assad.

"There is a shortage of bread in the city, electricity is cut and the majority of phone lines are too," he added.

Several residents of the coastal town, 280 kilometres (174 miles) northwest of Damascus, confirmed al-Shuhri's testimony, particularly the bread shortage.

Abdelbasset, an electrician, told AFP the situation was "extremely bad"

"The army was redeployed outside the city and the security forces and shabbiha (regime agents) conducted a number of arrests. The town is dead, shops are closed," he said.

"Banias is surrounded by tanks, no one can get in or out. It is like a prison," said Yasser, a shopkeeper.

"We cannot get bread anymore in Banias. Bread supplies were brought from (the city of) Tartus but that is not enough. The petrol stations are also closed," he added.

Yasser said: "Security forces were responsible for killing soldiers in Banias because they had refused to attack the city," an account which differed sharply from the official version of events.

The official Sana news agency had said nine soldiers, including two officers were killed on Sunday when their patrol was ambushed outside the coastal town, 280 kilometres northwest of Damascus.

Preacher Sheikh Mohammed said: "Several families evacuated women and children (to the outskirts of the city), because we are in the Ras Al-Nabee neighbourhood which was targetted by gunfire from Al-Quz neighbourhood.

"The bakers of the town do not have enough bread," he added.

The army has encircled Banias since Sunday, when regime agents opened fired on residents, particularly in front of mosques, killing four people and wounding 17, according to witnesses.

Meanwhile, a Facebook group called for fresh protests in Syria on Tuesday to show "loyalty with the martyrs, wounded and prisoners" after a bloody weekend crackdown on anti-regime demonstrators.

"Today, March 12, is the day of loyalty towards the martyrs, wounded and prisoners, who are the heroes of the free youth revolution," said the organisers on Facebook page the Syrian Revolution Against Bashar Al-Assad, which has played a key role in mobilising recent protests.

"We will shout slogans despite our wounds and hold peaceful sit-ins until we obtain our freedom," the group said. "We will not stop, nor backtrack. Our cause is clear. It is a revolution by the people for the people and the demands are clear. Our path is peaceful and the objective is freedom."

The Facebook call came after a bloody weekend crackdown that left at least 30 civilians dead in the flashpoint towns of Daraa and Banias.

Syrian human rights activists have reported a country-wide wave of arrests focused on protest participants and organisers.

Syrian students on Monday staged a rally, rare for Damascus, to express solidarity with protesters killed over the weekend.