Nato has told President Bashar al-Assad that any use of chemical weapons in his fight against rebel forces would be met by an international response.
Fighting has erupted in a Damascus suburb and around a Syrian army base as a truce marking a Muslim holiday crumbled almost before it had begun.
UN observers say 13 bodies have been discovered bound and shot in eastern Syria, days after a massacre of 108 civilians ignited a world outcry.
Syria has challenged the UN chief over the scope of a UN truce monitoring mission, resisting a larger presence as its army shelled targets in Homs.
Continued military bombardments in central Syria is dashing the prospects of a UN-brokered ceasefire taking hold.
Syrian activists have accused forces loyal to President Bashar al-Assad of bombarding rebel areas as a UN mission is expected to arrive in Damascus.
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/ 12 February 2012
Syrian forces are bombarding Homs in their drive to crush a revolt against President Bashar al-Assad, ahead of a meeting of Arab foreign ministers.
Western countries have been seeking a new strategy to end the violence in Syria, while President Bashar al-Assad’s forces continue to bomb districts.
Syrian President Bashar al-Assad has blamed "foreign planning" for a 10-month-old uprising in which thousands of people have been killed.
Fierce fighting has continued in Syria shortly before officials arrive to prepare for an Arab League effort to end nine months of bloodshed.
Syrian troops swept into Hama to break a strike by President Bashar al-Assad opponents, killing 10 people but facing resistance from armed insurgents.
Syrian tanks pounded Homs on Saturday and three people were killed, activists said, after one of the bloodiest days of the seven-month-old uprising.
Turkey says it would impose sanctions on Syria despite the blocking of any UN measures against Bashar al-Assad for his crackdown on violent dissent.
President Bashar al-Assad will give an interview to Syrian television on Sunday, state media said, as a United Nations team arrived in Damascus.