AMMAN (Reuters) - Syrian forces shot dead six civilians in an attack on Sunni districts in the mixed city of Banias on Saturday, rights campaigners said, raising sectarian tension in a country gripped by pro-democracy protests.
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, who are from the Alawite sect.
Banias has seen some of the most persistent demonstrations since unrest first erupted in the southern city of Deraa seven weeks ago, with activists calling for political freedom and an end to corruption.
Rights group Sawasiah said the number of civilians killed in the violence across the country had reached 800, a figure disputed by the government.
Army units with tanks entered Banias, a Mediterranean coastal city of 50,000 people, from several directions, advancing into Sunni districts but not Alawite neighbourhoods, the human rights campaigners said. Banias is around 70 percent Sunni Muslim and 30 percent Alawite.
Four women were killed when soldiers fired at a small all-women protest marching on the main coastal highway from Marqab village near Banias, they added.
"Residents are hearing the sound of shelling and heavy machineguns," one of the human rights campaigners said.
Rami Abdul Rahman, head of the Syrian Observatory for Human Rights based in London, earlier told Reuters regular and special army units were in the city.
"They are conducting search operation in several areas. The army has lists and is looking for people based on it," he said.
Most phone and Internet communication with Banias has been cut but the campaigners said they were able to contact several residents.
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."
Mobile 3G Internet services 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.
Syrian authorities have banned foreign media from reporting from the country.
Syrian forces earlier raided Marqab, arresting scores of men, women and teenagers, the Observatory said.
State authorities said Banias was a "centre 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.
Syrian President Bashar al-Assad has said the protesters are part of a foreign conspiracy to cause sectarian strife.
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.
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, alongside other sanctions, in response to Assad's violent crackdown.
The United States also imposed sanctions against figures in the Syrian government last week. On Friday it threatened to step up pressure to try to stop the violence.
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.
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.
Security forces killed four protesters in Deir al-Zor on Friday, 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.
A Western diplomat said 7,000 people had been arrested since mid-March.