Syria's Turkish border units 'head for Aleppo'
25 July 2012 Last updated at 10:51 GMT
The BBC's Ian Pannell says these rebels rounded up men they believe to be supporters of President Assad
Thousands of Syrian soldiers are being moved from the border with Turkey to join fierce fighting in the city of Aleppo, activists have claimed.
Rebels said their fighters had attacked columns of troops as they abandoned their posts in Jabal al-Zawiya area.
Aleppo, the country's second city, has seen fierce clashes all week, with the government deploying fighter jets and helicopters to beat back the rebels.
Government forces have largely repelled a rebel assault on Damascus.
Until recently, the two main cities had been relatively free of the violence that has wracked other parts of the country.
But a sustained assault by rebels earlier this month on the capital saw a dramatic upsurge in violence there.
Although government forces appear to have largely retaken control of Damascus, activists still say military helicopters are still attacking some parts of the city.
The focus of the fighting appears to have moved hundreds of miles north to Aleppo, a northern city regarded as the country's commercial hub.
The BBC's Ian Pannell, near Aleppo, says on Tuesday fighter jets strafed parts of the city, and civilians and rebel fighters had been killed in fighting.
It was thought to be the first time that fighter planes had been deployed in such a way since anti-regime protests began in March 2011.
Activists said fighting continued throughout the city overnight.
In other developments
Russia's foreign ministry says it has received "firm assurances" that regime's chemical weapons stockpile is "fully safeguarded"
Opposition activists say Syria's envoy to Cyprus, Lamia Hariri, has defected to the opposition; the fate of her husband, who is ambassador to the United Arab Emirates, remains unclear
Russian Foreign Minister Sergei Lavrov lambasts the US for failing to condemn the killings of top regime figures last week, saying the US position "is directly justifying terrorism"
Early on Wednesday opposition activists said large numbers of troops began withdrawing from the Turkish border.
An activist called Abdelrahman Bakran told Reuters news agency that rebels had attacked the rear of a column of troops along the main road to Aleppo.
Colonel Abdel Jabbar al-Oqaidi, a spokesman for the rebel Free Syrian Army, told AFP news agency the troops were being redeployed to protect Aleppo because it was more strategically important.
Foreign journalists work under intense restrictions in Syria so reports by both sides are hard to verify.
Aleppo is just 60km (40 miles) from the Turkish border.
In recent weeks, the rebels have taken control of several posts along the 900km frontier, which has been plagued by attacks on lorries and fighting between rebels and government forces.
Turkey announced on Wednesday that it was shutting the remaining posts to lorries because of "security concerns".
Turkish officials said refugees would still be allowed through the border.
Analysts say the measure is an economic sanction, and that the embargo will hurt the regime, which relies on cross-border trade.