BEIRUT, Lebanon -- Syrian tanks shelled the central city of Hama and parts of Homs came under mortar fire on Tuesday, opposition activists said, on the day President Bashar Assad had agreed to halt the use of heavy weapons and withdraw forces from urban areas.
Tanks were still present in both cities, activists said.
A collapse of the truce deal by U.N.-Arab League envoy Kofi Annan could move Syria closer to an all-out civil war. A 13-month uprising has turned increasingly violent in response to a brutal regime crackdown.
"Shelling woke me this morning at 8:30 a.m. (2:30 a.m. ET) and I can now hear one shell every 10 minutes or so," said Waleed Fares, describing what he said was mortar fire striking neighborhoods in the center and east of Homs, the hub of a 13-month-old uprising.
In Hama, Manhal Abu Bakr reported hearing shelling overnight and said tanks were still patrolling the city.
"At 2 a.m. (8 p.m. Monday) we heard two shells fall and the sound of tanks moving around the streets," he said.
"There is no gunfire now. They shell us at night so that it is hard to film," he said over Skype. Internet video, which Abu Bakr said was filmed in Hama overnight, showed nighttime explosions in a built-up district.
The Britain-based Syrian Observatory for Human Rights said most cities were relatively calm on Tuesday after heavy bloodshed in recent days, but reported no clear sign of troop withdrawals.
Syrian troops' message: 'We are present'
There were no immediate reports of action by fighters of the rebel Free Syrian Army, whose commanders have said they will order a cease-fire only if they are satisfied that Assad's forces have indeed pulled back and stopped offensives.
The Observatory said there was an overnight bombardment in the town of Mara in Syria's northern province of Aleppo.
Syrian troops have fired across the border into Turkey, hitting a refugee camp. It's the latest incident suggesting that a cease-fire meant to take effect this week is unlikely to go ahead. ITV's Richard Pallot reports.
In Douma, a suburb of the capital Damascus, an activist said tanks were still on the fringes of town on Tuesday morning.
Residents of the southern city of Deraa, where the popular revolt against Assad erupted in March 2011, reported sporadic gunfire.
"Security is everywhere and you feel they have redeployed in key locations," said Nayef Hassan, an engineer.
Security forces and the army remained stationed in Deraa, said an activist who called himself Abu Firas, and security checkpoints still separated districts of the old city.
"The troops at checkpoints are appearing in strength to say 'we are present'," he said.
Reuters and The Associated Press contributed to this report.
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