Hama saw the largest anti-government demonstration staged in the country since March [AFP]

About 1,000 people have fled Syria's central city of Hama fearing another military crackdown on protests calling for the ouster of President Bashar al-Assad's regime, a Syrian rights group said.

The Syrian Observatory for Human Rights, based in London, said the residents had headed for Salamiyah, a town 30km from Hama, on Thursday, after security forces killed at least 23 civilians there and conducted mass arrests since Tuesday.

Hama, which saw about 500,000 people take part in an anti-government rally last Friday, has become the most recent flashpoint city of demonstrations that have rocked the country since March.

Ammar Qurabi, head of the National Organisation for Human Rights, said on Wednesday that an influx of troops following the massive Friday protest had brought a dramatic escalation of "killings and arrests in the city".

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But Al-Watan, a state-run newspaper, said on Thursday that the situation in Hama was calm and the barricades erected in the streets by protesters to keep security forces out had been dismantled.

The newspaper said authorities had told demonstrators to avoid any confrontations and clear the streets so residents could go to work. They also told protesters to avoid a "last resort" military operation, the paper said. 

According to Al-Watan, the protesters were calling for Hama's former governor - who was sacked following the protest last Friday - to be reinstated. They also called for detained demonstrators to be freed; for a pledge that the security forces would not intervene and for a guarantee of freedom to demonstrate.

Hama has been a symbolic city of opposition since the 1982 crackdown on a revolt by the banned Muslim Brotherhood against then-president Hafez al-Assad, father of the present leader. About 20,000 people were killed in the crackdown.