Syria’s army has advanced into the southern city of Deraa, using tanks to support troops amid an intensified effort to curb popular protests.
One activist was quoted as saying that security forces were “firing in all directions”, and at least five people were reportedly killed.
Witnesses also said security forces had opened fire in a suburb of Damascus.
A prominent human rights campaigner said President Bashar al-Assad had launched a “savage war” on protesters.
In the US, the Obama administration is considering imposing sanctions on senior Syrian officials to pressure the regime to stop its violent crackdown, Reuters news agency quoted a government official as saying.