Reports say fighting in the strategic Syrian town of Qusair has intensified.
State media reported on May 25 that troops loyal to President Bashar al-Assad had launched a three-pronged attack on the rebel-held town and were making big advances.
The rebels said they were under heavy bombardment and that elite troops from the army and Lebanese Hizballah fighters were leading the offensive.
In Istanbul, Syria's opposition resumed talks aimed at creating a united front ahead of a proposed international peace conference in Geneva.
Speaking to journalists in Istanbul on May 25, George Sabra, acting chairman of the Syrian National Council, requested immediate help.
"We are calling our brothers and sisters from the revolution and Free Syrian Army to support and give weapons to their brothers and sisters in Muhayamiya and Qusair and the area around Damascus," he said.
Sabra described the siege of Qusair by government troops as "terrorism" and criticized the international community for failing to help.
"This is a terrorism that has never happened before in the history of the world," he said. "And this is happening in front of the whole world and everybody is seeing this. What is going on in Syria now is allowing terrorism and extremism and it is allowing criminals to kill people and it allows barbarians to disrespect humanity."
The Syrian military began an offensive to recapture Qusair, located between Homs and the Lebanese border, a week ago.
The offensive is seen as an attempt by Assad to secure the coastal region. The area is home to his Alawite minority sect, a branch of Shi'ite Islam.
His regime is supported by Shi'ite Iran and Hizballah against predominantly Sunni rebels backed by Saudi Arabia and Qatar.
The United States and Russia are pushing for an international peace conference in Geneva to end more than two years of conflict inside Syria that has left some 80,000 dead.
With reporting by Reuters, dpa, and AFP