SANA, Associated Press
In this photo released by the Syrian official news agency SANA, Syrian government soldiers stand guard on the roof of Aleppo prison in Aleppo, Syria, Thursday, May 22, 2014. Syrian troops backed by airstrikes broke a yearlong rebel siege of a prison in the northern city of Aleppo Thursday, allowing President Bashar Assad's forces to close in on a nearby command center of a coalition of Islamist rebel groups, opposition activists said.

BEIRUT — Syrian rebels and government forces have agreed to a truce in an opposition-held area near the central city of Homs, activists said Saturday.

The cease-fire, which started on Friday, comes as troops loyal to President Bashar Assad are trying to seize as many rebel-held parts of major urban centers as possible ahead of the June 3 presidential elections.

Assad is widely expected to win a third, seven-year mandate, but opposition activists have criticized the vote as being illegitimate because it is taking place amid a raging civil war. Syria's conflict, which began as an uprising against Assad's rule, is now in its fourth year and has killed about 160,000 people, activists say.

The truce in al-Waar, which lies across the Orontes River from Homs, is meant to enable the warring sites to negotiate an agreement that will allow the rebels to leave the area without being attacked, or later arrested.

A Syrian activist who uses the name Thaer Khalidiya said the truce went into effect on Friday and was to last for three days, until Sunday night.

Rami Abdurrahman of the Britain-based Syrian Observatory for Human Rights and the Hezbollah channel al-Manar, which supports Assad, also reported the cease-fire.

It is similar to a cease-fire agreed on in early May that ultimately allowed for the evacuation of hundreds of rebels from opposition-held parts of Old Homs.

Assad's forces have been combining bombings of besieged, opposition-held areas with negotiated cease-fires and evacuation deals to reclaim rebel-held territory.

Al-Waar has been under a government blockade for about six months that has prevented food and fuel from entering the area, where tens of thousands of civilians live.

Khalidiya, the activist, said that although rebels were quite strong in al-Waar, they were under pressure from the residents to leave the area.

He said many of local residents feared they would suffer deprivation and hunger, akin to what civilians in rebel-held parts of Homs experienced, if the siege in al-Waar continued for much longer.

Pro-government forces control the Syrian capital, Damascus, and recently assumed control of all of Homs. They have also stepped up their assault in the northern city of Aleppo, Syria's largest, to take back rebel-held areas.

But government-held areas are not entirely secure. A car bomb killed two people in an upscale part of Damascus on Saturday.

On Thursday night, a mortar attack on Assad's supporters gathered at an election campaign tent in the southern city of Daraa killed 39 people and wounding 205 others, Syrian state TV said Friday.