Syrian military planes have launched air raids in Damascus province after overnight bombardments and clashes across the country.
The raids on Friday came as Syrians took to the streets in fresh nationwide rallies against President Bashar al-Assad.
Government forces in the suburbs of Damascus have been trying to take back areas they had lost after rebel attacks on military checkpoints and activists say that further air raids were expected there.
In Damascus city, several rockets hit the Qaboon district in the northeast of the capital, activists said, while clashes between rebels and the army erupted in the southern neighbourhood of Qadam, which was also bombarded.
Fighting was also reported in Daraya, a town in southern Damascus, which Assad's forces have been trying to retake for weeks.
There were also clashes in Yalda in the south and Douma in the northeast, as well as an attack on a military position northeast of Damascus between the provincial town of Irbin and the suburb of Harasta.
In Aleppo, Syria's northern commercial hub, clashes took place between rebel fighters and army forces around an air force intelligence building in the Zahira quarter, a neighbourhood that has been surrounded by rebels for weeks.
Overnight shelling was also reported in the central provinces of Hama and Homs.
At least 142 people were reported killed in violence across Syria. Activists say that more than 40,000 have been killed since an uprising against Assad began in mid-March 2011.
Meanwhile, officials at Turkey's foreign ministry on Friday said two Syrian air force generals have defected and crossed the border.
The officials said the two generals were "regional Syrian Air Force commanders" and are now in a camp where army defectors stay in Turkey.
They refused to give the generals' identities or say how they escaped from Syria. They spoke anonymously as they were not authorised to talk to the press.
The defection comes days after the commander of Syria's military police Major General Abdul-Aziz Jassem al-Shallal defected to Turkey.
Shallal is among the most senior members of Assad's military to defect. Dozens of Syrian generals have defected since the uprising began.