AMMAN (Reuters) - Syrian tanks attacked the mostly Sunni Muslim city of Banias on Saturday, a rights campaigner said, raising sectarian tension in a country gripped by protests against the rule of President Bashar al-Assad.
The campaigner told Reuters that Syrian forces fired at a small all-women protest marching on the main coastal highway from Marqab village near Banias, killing three of them.
The attack came hours after the United States, reacting to the death of 27 protesters on Friday, threatened to take new steps against Syria's rulers, from the Alawite sect, unless they stopped killing and harassing their people.
The army entered Banias, a Mediterranean coastal city of 50,000 people, from three directions, advancing into Sunni districts but not Alawite neighborhoods, the campaigner said.
Most communication with Banias has been cut but the campaigner said he was able to contact several residents.
"Residents are reporting the sound of heavy gunfire and seeing Syrian navy boats off the Banias coast. Sunni and mixed neighborhoods are totally besieged now," said the campaigner, who did not want to be identified for security reasons.
Rami Abdul Rahman, head of the Syrian Observatory for Human Rights based in London, told Reuters that regular army units were present in the center of Banias but the authorities had now sent special units into the northern side of the city.
"They are conducting search operation in several areas. The army has lists and looking for people based on it," he said.
"They have raided Bayda, Basateen and the Baseya suburbs."
Rights group Sawasiah said in statement that the number of civilians killed since pro-democracy demonstrations broke out seven weeks ago has reached 800. It added that there were cuts in landline, Internet and cellphone lines with Banias as army units backed by tanks swept into its districts.
Syrian authorities have banned foreign media from reporting from the country.
Sawasiah said the authorities had intensified a clampdown on communication networks to disrupt the flow of information about their "bloody repression of non-violent demonstrators."
Cellphone 3G Internet service by the country's two operators has been cut in Damascus as well since Friday, Sawasiah said.
Syrian tycoon Rami Makhlouf, Assad's cousin, owns the country's largest operator Syriatel, while South African group MTN controls the second operator.
Banias has seen some of the most persistent demonstrations since unrest erupted in the southern city of Deraa calling for political freedom and an end to corruption.
State authorities said Banias was a "center of Salafist terrorism" and that armed groups had killed soldiers near the city. Salafism is an ultra-conservative brand of Sunni Islam.
Civic leaders in Banias denied the accusation and said the government was trying to spread fear among Alawites, who occupy most senior positions in the army and security apparatus.
Assad has asserted that the protesters are part of a foreign conspiracy to cause sectarian strife, something they deny too.
His father, Hafez al-Assad, who ruled for 30 years until his death in 2000, brutally suppressed an armed Islamist uprising in 1982 in which around 30,000 people were killed.
Majority Sunni districts of Banias have been under protester control since Assad loyalists, known as "al-shabbiha," fired at residents from speeding cars on April 10, after a large demonstration that demanded the "overthrow of the regime."
International criticism has increased against Assad, who is trying to preserve his family's 41-year-old grip on power in the country of 20 million people.
European Union governments agreed on Friday to impose asset freezes and travel restrictions on up to 14 Syrian officials as well as some sanctions in response to Assad's violent crackdown.
The United States adopted sanctions of its own last week against some figures in the Syrian government. On Friday it threatened to step up the pressure to try to stop the violence which rights campaigners say has killed more than 800 people.
But the new Western sanctions are seen as insufficient to sway Syria's ruling elite in the near term and tougher steps are unlikely as they would penalize mainly ordinary Syrians.
Assad also benefits from a lack of pressure on him from fellow autocratic rulers in the Arab League, analysts say.
There are also international fears of disorder in Syria if Assad is overthrown, since the country straddles many of the fault lines of Middle East conflicts.
Syrian officials give a lower death toll from the unrest and say half the fatalities have been soldiers and police, blaming "armed terrorist groups." They say demonstrators are few in number and do not represent the majority of Syrians.
Protests broke out after Friday prayers in cities across Syria, from Banias on the Mediterranean coast to Qamishly in the Kurdish east. The bloodiest confrontation was in Homs where 15 protesters were killed, activist Ammar Qurabi said.
The state news agency SANA said on Saturday that "terrorist groups" had killed 11 soldiers and policemen in Homs, listing the names of those dead. The figure was put at 5 on Friday.
Four protesters were killed by security forces in Deir al-Zor, a local tribal leader said, the first deaths reported from the region that produces most of Syria's 380,000 barrels per day of oil in seven weeks of unrest.
A Western diplomat said 7,000 people had been arrested since mid-March.
Additional reporting by Mariam Karouny; editing by Mark Heinrich