Some of Aleppo’s residential neighbourhoods have come under rebel mortars, which have already destroyed a post office and a Roman Catholic church.
Heavy fighting continues outside Abu Kamal near the Iraqi border, where the rebels are holding an army base, and around the eastern city of Deir ez-Zor, where oil fields are under rebel attack.
On Sunday, the Syrian army continued its offensive against the rebels to the east of Damascus.
The centre of the operation which has been going on for over a week has shifted from the suburbs of Damascus farther east, the Lebanese Al Mayadeen TV channel reports.
Artillery shelling continues south of Damascus and clashes persist in Aleppo, Hama and Homs.
The conflict in Syria has been going on since March 2011. According to the UN, 17,000 people have fallen victim to the conflict.
Syrian state television reported twin bombings near security service buildings in the centre of the capital on Sunday and said they wounded four people. Free Syrian Army claimed responsibility for the attack.
The attack took place near a security services building which is tasked with protecting the army's General Staff, whose headquarters is located in the central Umayyad Square, some three kilometres (two miles) away.
Abu Remmaneh is an upscale neighbourhood in the heart of Damascus, and is home to several embassies.
The Ahfad al-Rasul (Grandchildren of the Prophet) brigade of the rebel Free Syrian Army claimed responsibility for the attack in a statement on Facebook, in which it also threatened to attack President Bashar al-Assad's palace.
"This operation was carried out in response to the massacres in Daraya," said the statement, referring to the killing last week of at least 330 people in a town near Damascus. Regime and rebel forces blamed each other for the massacre.
The group said it had prepared the twin bombings with the help of two other rebel groups.
Also on Sunday, state media reported that a car bomb explosion near a mosque at Sbeneh in the southern outskirts of the capital on Saturday killed 15 people. Sbeneh is a poor neighbourhood where anti-government sentiment is strong.
The latest explosions come after a car blast in the southeastern suburb of Jaramana on August 28 which killed at least 27 people, according to the Syrian Observatory for Human Rights.
Vesti, RIA, AFP