Syrian warships have joined a military assault on protesters in the northern port city of Latakia, activists say.
At least 19 men and women have been killed in the operation, according to activists and human rights teams.
Explosions and gunfire have been noted in several districts of the city which have seen big protests in opposition to the Syrian authorities.
More than 1,700 people have reportedly died in the 6-month uprising in opposition to the rule of President Bashar al-Assad.
The operation began on Saturday with armoured cars and troops shifting in.
'Residents flee' Some 20 tanks and staff carriers ended up stated to be using element in the Latakia assault alongside with at the very least two gunboats.
One witness informed Reuters information agency by telephone: "I can see the silhouettes of two grey [naval] vessels. They are firing their guns and the influence is landing on al-Ramleh, al-Filistini and al-Shaab neighbourhoods."
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Jim Muir BBC Reports, Beirut
Latakia was one of the cities to be caught up in the revolt quickly immediately after it erupted in mid-March. Even with repeated attempts by the regime to stifle defiance, it retains breaking out.
It is a hypersensitive city. Its inhabitants is 600,000 or so, and it has a Sunni Muslim vast majority, as does the country, but there are also areas dominated by President Assad's minority Alawite community.
The present punishment is becoming meted out to mostly Sunni places, a fact that could additional aggravate sectarian tensions previously sensitised by the circumstance.
A report on state television denied there had been any naval shelling.
Activists stated at minimum two folks have been killed and 15 wounded in Saturday's attacks.
They mentioned a big amount of citizens had fled the city and that telephones and net connections had been cut off.
International journalists face serious limits in functioning in Syria, and it is challenging to verify reports.
1000's of folks ended up mentioned to have occur on to the streets of Latakia on Friday to demonstrate in opposition to the authorities.
Novice video clip footage posted on the World wide web also confirmed what appeared to be armoured personnel in the streets.
Latakia has noticed many anti-government protests in the previous six months.
Tens of countless numbers of folks had come out on to the streets across the country yet again on Friday to protest.
The Syrian Observatory said that a large quantity of troops had also moved into the Saqba and Hamriya districts of the capital Damascus on Sunday, with gunfire heard in both suburbs.
Crackdown 'intensifying' Syria has come under enhanced diplomatic stress in the past week to halt its crackdown on dissent.
The US has imposed sanctions on Damascus and has explained these could be increased, even though calling on other countries to comply with.
Saudi Arabia, Bahrain and Kuwait have all recalled their ambassadors, whilst Turkish International Minister Ahmet Davutoglu has described the strategies employed by the Syrian security forces as "unacceptable".
Nevertheless, it appears the crackdown has intensified, with troops storming a number of towns and cities.
Mr Assad has reiterated claims of political reform, while remaining adamant his authorities would proceed to go after the "terrorist teams" he has blamed for the unrest.
Protests have been targeted in Homs, Hama, Damascus, Deir al-Zour in the east, Deraa in the south and Aleppo and Idlib in the vicinity of Turkey's border ( via bbc.co.uk ).