America has confirmed the defections of two more senior Syrian diplomats, saying it was further evidence that President Bashar al Assad's days are "numbered".
"We can confirm the defections of Syrian ambassadors to both the UAE and Cyprus," White House spokesman Jay Carney told reporters aboard Air Force One.
Mr Carney said the move showed "senior officials around the Assad inner circle are fleeing the government because of the heinous actions taken by Assad against his own people, and the recognition that Assad's days are numbered".
Earlier, a high-level source told reporters that Syria's charge d'affaires in Cyprus, Lamia Hariri, had defected from the regime.
An opposition activist in the country confirmed that Ms Hariri's husband, Syria's ambassador to the United Arab Emirates, Abdel Latif al Dabbagh, had also defected.
Qatar-based al Jazeera television said Mr Dabbagh had defected, though it did not say where he was.
But a senior State Department official confirmed that "Dabbagh has defected to Qatar".
Nawaf Fares, Syria's ambassador to Iraq, left for Qatar this month after publicly renouncing his post.
Two Syrian brigadier generals also entered Turkey on Tuesday, bringing to 27 the number of generals who have defected, a foreign ministry official told reporters.
On Wednesday, the Syrian army and rebels sent reinforcements to Aleppo to join the intensifying battle for the country's second city.
Helicopter gunships attacked several neighbourhoods of the commercial capital, causing deaths and injuries, according to the Syrian Observatory for Human Rights said.
The UK-based observatory also reported fighting in the Al-Hajar Al-Aswad district of Damascus, one of the last remaining rebel bastions after 10 days of violence in the capital.
Helicopter gunships and heavy machinegun fire pounded the embattled southern neighbourhood, the observatory said.
Nationwide at least 87 people were killed on Wednesday, most of them civilians, after 158 people died on Tuesday, the organisation said.
In Hama province, in central Syria, a couple and their two children were reportedly killed as they tried to flee shelling. A video distributed by the observatory showed footage of the bodies.