Syria says US 'interfering' as ambassador visits Hama
Syria has accused the US of "interfering" in its affairs after the US ambassador to the country travelled to the flashpoint city of Hama.
The Syrian foreign ministry said the visit by Robert Ford was "obvious proof" of US involvement in continuing protests in the country.
Earlier, the US State Department said Mr Ford's visit was to show solidarity with protesters.
Hundreds of Hama residents have fled fearing an assault by security forces.
Tanks are stationed outside the city and at least 22 people have been shot dead in recent days.
Washington says Mr Ford hopes to stay in Hama for anti-government protests which normally follow Friday prayers.
The BBC's Kim Ghattas in Washington says the ambassador's presence in Hama could dissuade Syrian President Bashar al-Assad from launching an all-out assault on the city.
But the move has angered Damascus.
"The presence of the US ambassador in Hama without previous permission is obvious proof of the implication of the United States in the ongoing events, and of their attempts to increase (tensions), which damage Syria's security and stability," the foreign ministry said in a statement.
Last Friday's protest in Hama was one of the largest in three months of demonstrations across Syria.
A day later, Mr Assad sacked local governor Ahmad Khaled Abdel Aziz for reportedly failing to suppress the unrest.
Security forces swept in on Monday in an attempt to regain control of the city, but tanks have so far remained outside.
Significance of Hama
Hama - a bastion of dissidence - occupies a significant place in the history of modern Syria. In 1982, then-President Hafez al-Assad, father of Bashar, sent in troops to quell an uprising by the Sunni opposition Muslim Brotherhood. Tens of thousands were killed and the town flattened. The operation was led by the president's brother, Rifaat.
Similarly, current President Bashar Assad has turned to his own brother, Maher, who commands the army's elite Fourth Division, to deal with the unrest.
Hama, with a population 800,000, has seen some of the biggest protests and worst violence in Syria's 2011 uprising.
On Thursday, residents blocked streets with burning tyres in attempts to keep out bus-loads of security forces, witnesses said.
Dozens of families were said to be fleeing the city.
US State Department spokeswoman Victoria Nuland said Washington was "greatly concerned about the situation in Hama".
"The fundamental intention (of Mr Ford's visit) was to make absolutely clear with his physical presence that we stand with those Syrians who are expressing their right to speak for change," she said.
The Obama administration has been criticised for not reacting strongly enough to the crackdown in Syria. Washington has warned President Assad that he is running out of time to reform but has yet to call on him to step down.
Opposition activists say that more than 1,300 protesters have died across the country since protests began in March.
In 1982, Hama was the scene of the ruthless suppression of an uprising against President Assad's father.