Syria set for ‘day of defiance’

Tanks are reported to have withdrawn from the city of Deraa, where a human rights groups says the government has carried out a 10-day "massacre".

But security forces are reported to have gathered in other urban areas, including the coastal town of Baniyas.

More than 500 Syrians are thought to have been killed during attempts to quell seven weeks of protests.

At least 2,500 others have been detained as part of a violent crackdown that the US has described as "barbaric".

In cities across Syria protesters are calling for greater political rights and personal freedoms. Some are calling for the downfall of the regime of President Bashar al-Assad.

People are expected to gather again after prayers on Friday, which have become a regular focal point for protests in the Arab world in 2011.

The unrest in Syria poses the most serious challenge to four decades of rule by the Assad family in one of the Arab world's most tightly controlled countries.

Foreign journalists are not allowed to enter the country, so it is difficult to verify the reports of deaths.

One doctor, who said he planned to join those demonstrating, said the "indiscriminate killings and inhumane arrests have generated total disgust among the average Syrian".

Military units were reported to be deploying elsewhere on Thursday, including around the coastal town of Baniyas, home to one of Syria's two oil refineries.

Four armoured personnel carriers, several tanks and a bus carrying soldiers were seen by one eyewitness quoted by the Associated Press.

Hundreds of families were said to be fleeing the area, fearing that Banias - like the city of Deraa - could come under siege.

A UN humanitarian team is expected to visit Deraa in the coming days, the organisation's deputy spokesman Farhan Haq said on Thursday, following an appeal to President Bashar al-Assad by Secretary-General Ban Ki-moon.

Over the past two days there has also been an increased military presence also in the coastal towns of Homs and Rastan. Troops have also gathered in the Damascus suburbs of Erbin, Saqba, Douma and in the town of Tel, north of the capital.

In Washington, state department spokesman Mark Toner said the US continues to "press Assad's regime to desist in its violent behaviour".

The Damascus Center for Human Rights Studies says snipers and anti-aircraft machine guns were used to fire on unarmed civilians in the southern city and recent amateur video appears to show dozens of unarmed protesters being shot and bleeding to death on the streets.

It has labelled the killings in Deraa a "massacre".

The government says it is taking action against "elements of terrorist groups... to restore security, peace and stability".