Amman: Syrian tanks surrounded Hama on Tuesday, residents and activists said, threatening a large-scale assault on the city after the biggest protests against President Bashar Al Assad's rule.

Hundreds of youths blocked roads leading to the city's main residential neighbourhoods with garbage containers, wood and metal to try to prevent a possible advance. Inhabitants joined in their shouts of "God is greatest," from balconies and rooftops, residents said.

Dawn raids kill three

Tanks and armoured vehicles moved overnight to the edges of the city, including 30 seen near a flyover on a road leading west, they said, a day after hundreds of troops and security police entered Hama at dawn in buses, killing at least three people in raids on main neighbourhoods.

Hama, scene of a bloody crackdown by Assad's father nearly 30 years ago, has witnessed some of the biggest demonstrations and highest death tolls in Syria's 14-week uprising, inspired by revolts across the Arab world.

Large-scale protests

"Assad may wait to see whether large-scale protests in Hama continue. He knows that using military aggression against peaceful demonstrations in a symbolic place like Hama would lose him support even from Russia and China," Syrian activist Mohammad Abdallah told Reuters from exile in Washington.

The two countries have opposed a United Nations Security Council resolution proposed by the West against Syria, helping Assad withstand mounting international isolation.