Syrian president Bashar al Assad says the uprising in his country is a foreign plot against the whole region.
His vow to defeat the conspiracy at any price comes amid claims that government forces massacred more than 300 people in Daraya, southwest of the capital, Damascus.
Rebels in Syria say 320 bodies, including those of women and children, have now been found in Daraya.
Many had gunshot wounds to the head and chest. Some had been killed at close range.
The opposition says they were executed by troops in house-to-house raids.
Forces loyal to the president are accused of mass summary executions.
The BBC reports Daraya came under assault on Saturday, after days of heavy bombardment.
State television says Daraya has been "cleansed of terrorist remnants".
A member of the Syrian National Council, Radwan Ziadeh, is originally from Daraya, and has been in regular contact with his family there.
Speaking from Istanbul, he says they live in constant fear for their lives and can't leave their homes because they will be attacked by security forces or snipers.
There is no independent confirmation of the claim because of restrictions on foreign media in Syria.
The chairman of the UN Human Rights Council's Independent Commission of Inquiry on Syria, Paulo Pinheiro, told the BBC the killings might constitute a war crime.
In a separate development, the head of the United Nations mission to Syria left the country after the mission was wound up.
Lieutenant General Babacar Gaye of Senegal joined a UN convoy to Lebanon on Saturday.