Syrian rebels today braced for a new assault on their beleaguered stronghold of Qusayr by the army and its Hezbollah allies, who were bolstering positions north of the town, a watchdog said.
Fears of another move on the town renewed concerns about the fate of an unknown number of civilians still trapped there, including an estimated 1,000 wounded.
UN Secretary General Ban Ki-moon demanded that both sides allow civilians to flee.
Rami Abdel Rahman, director of the Syrian Observatory for Human Rights watchdog, told AFP that "there are ongoing clashes in northern Qusayr, and the opposition fighters are fighting with everything they've got.
The group said at least 15 tanks were massed north of Qusayr, a key strategic prize for both the regime and the rebels. It sits on the route linking Damascus to the Mediterranean coast, and lies near the Lebanese border, providing a key rebel conduit for weapons and fighters.
The Syrian opposition yesterday said that rebel reinforcements had reached the area.
The fight for the town, which began nearly two weeks ago, has raised fears about the safety of thousands of civilians.
Abdel Rahman, whose watchdog relies of a network of activists, doctors and lawyers on the ground, said around 1,000 wounded people were trapped inside Qusayr.
"The medical situation is very bad," he said.
In New York, UN chief Ban Ki-moon urged "all sides to do their utmost to avoid civilian casualties," spokesman Martin Nesirky said in a statement.
"He also reminds the government of its responsibility to protect civilians who come under its control, including from the threat of militias. He calls on the warring parties to allow trapped civilians to escape the town."
The opposition Syrian National Coalition saluted rebels in Qusayr, including the reinforcements.
"The heroes of the Free Syrian Army prove every day that they are worthy of the responsibility that the people have entrusted them with," it said.
"The people will continue their struggle to liberate their land, whatever it takes, and will force Hezbollah to withdraw its forces from all of Syria."
The powerful Lebanese Shiite group, a staunch ally of President Bashar al-Assad's regime, has dispatched thousands of fighters to help put down the uprising that began more than two years ago with peaceful protests.
Members of Lebanon's Sunni Muslim community have also crossed the border to fight alongside the Sunni-led rebels, encouraged by local clerics.
Late yesterday, influential Muslim cleric Yusuf al-Qaradawi urged Sunnis throughout the region to follow suit and join the Syria uprising.
"Every Muslim trained to fight and capable of doing that (must) make himself available" to support the Syrian rebels, the cleric said at a rally.
The continued fighting has raised concerns about the prospects for a peace conference expected to convene in Geneva this month to seek a political solution to the conflict.
