Military aircraft of President Bashar Assad's regime have reportedly struck several rebel positions around the country. The UN on Sunday said the flow of refugees trying to reach Jordan had virtually dried up.
The UN refugee agency said only five Syrians safely crossed into neighboring Jordan on Sunday, compared to an average of 700 daily crossings last week.
Syrian activists said the halt was caused by an army offensive along the Syria-Jordan border, claiming this had slowed the flow to a "standstill."
Up to 10,000 internally displaced Syrians, mostly women and children, were stranded inside Syria, according to activists and relief officials quoted by the German news agency DPA.
The Britain-based Syrian Observatory for Human Rights said at least 40 people were killed on Sunday as Assad administration aircraft, including helicopters, struck at rebel bastions in central Homs province, Deir Ezzor to the east, several suburbs of Damascus and Jebel al-Akrad in the coastal province of Latakia.
A rebel commander told the news agency AFP that his forces had destroyed two fighter planes in Orm.
Colonel Amhad Abdul Wahab of the Free Syrian Army claimed that rebel forces "control most of the country."
His claim coincided with a rare meeting in Damascus of political parties of Syria's so-called "internal opposition." They said Sunday's gathering took place after a promise of protection from the two UN Security Council permanent members, China and Russia, which have supported Assad in the conflict.
AFP, meanwhile, carried speculation that Assad's only sister, Bushra, and her five children had moved to Dubai. The agency cited Syrian expatriates living in the emirate.
Bushra's husband General Assef Shawkat, an army deputy chief of staff, was killed along with three other high-ranking officials in a July bombing in Damascus.
Ahead of Tuesday's opening of the UN General Assembly, German Foreign Minister Guido Westerwelle urged world leaders to signal the need for a "new beginning" in Syria.
Westerwelle was speaking before a meeting in New York with UN Secretary General Ban Ki-moon.
Germany currently holds the presidency of the UN Security Council.
ipj/msh (dpa, AFP, Reuters)