Syrian security forces are reported to have intensified their operation against anti-government protesters in the city of Homs. Residents report heavy gunfire.
About 50 people have been reported dead over the past few days. Syrian authorities said soldiers came under machine-gun fire and grenade attack.
Some of the fighting is reportedly between Sunni and Alawite communities.
Both the government and opposition accuse each other of encouraging sectarian violence since an uprising against President Bashar al-Assad began in mid-March.
The government blames the unrest on ''terrorists and armed criminal gangs'' backed by a foreign conspiracy.
International journalists have been denied access to Syria, making it difficult to verify reports.
The Assad family has ruled Syria for more than four decades.
