Lt. Col. Mohamed Hamdo of the Free Syrian Army, an opposition group of defected Syrian military personnel, said protesters have until Monday night to end their demonstrations against the regime of President Bashar Assad, CNN reported.
On state-run media, the government has not acknowledged a deadline, which activists said was issued Friday, CNN said.
Reports of violence don't square with information distributed by state-run Syrian Arab News Agency, which said more than 3,000 candidates are competing for seats in the Homs region alone in local elections, activists said. SANA called the elections part of the "process of building institutions, promoting democracy and achieving the comprehensive reform process" led by Assad.
Fighting broke out between security forces and defectors in Daraa and Idlib, the London-based Syrian Observatory for Human Rights said.
The Local Coordination Committees of Syria said checkpoints in Daraa were targets of tanks and gunfire. Hamdo said the military dug trenches around Homs.
The Syrian National Council, the country's leading opposition movement, said information from activists on the ground "indicate that the regime is paving the way to commit a massacre in order to extinguish the revolution in Homs and to discipline, by example, other Syrian cities that have joined the revolution."
Hamdo told CNN Homs residents have been cut off from basic needs. The Syrian government denied reports water and electricity were cut off, SANA said.
Opposition figures initiated a nationwide anti-government strike Sunday, calling it a "strike of dignity." However, SANA reported people as saying there was no strike.
The tension spilled into Amman, Jordan, Sunday when weekly protests outside Syria's embassy became a fight between opposition activists and embassy employees, Israeli media network Arutz Sheva said. Each side blamed the other for the fracas.
The United Nations has said more than 4,000 people have died in Syria since the crackdown began in mid-March.
The Arab League announced it will conduct emergency meetings this week in Cairo to "discuss the Arab response to a message from Syrian Foreign Minister Walid Moallem approving the signing of an agreement on an Arab League observation mission to Syria "with conditions," a statement on Egypt's state-run Middle East News Agency indicated.
World leaders have condemned Syria's crackdown and called on the Assad regime to end the violence against the opposition.