"God damn your soul Hafez, for fathering Bashar al-Assad," protesters chanted, referring to the autocratic president's predecessor and father Hafez al-Assad. "Freedom forever, whether you like it or not."

One carried a placard with "Aazaz" written in letters dripping in red, in memory of the some 40 reported victims of an air strike in the nearby town on Wednesday that rights groups labelled another other regime atrocity.

The attack, which flattened a string of houses, wounded at least 100 more people and sent 2,000 people fleeing across the border into nearby Turkey, where some of the victims also died.

Young men sprayed water on the protesters as they marched in the sweltering midday sun past butchers slaughtering the first sheep for the Eid al-Fitr feast marking the end of the fasting month of Ramadan.

Several other demonstrations had been called across rebel-controlled towns in the north, as is the case almost every Friday, under the slogan this week of "If our Free Army is united, victory is assured".

"Marea can be considered the birthplace of the revolution, this is where the first graffiti against Assad started appearing on the walls," claimed one demonstrator in his 40s, who changed his name from Bashar to Bashir this year.

"For decades demonstrations were banned, so every protest is a celebration of our freedom. But we are also honouring the dead of Aazaz and Qadi Askar," said Abu Khaled, another protester.

At least 10 civilians were killed on Thursday in an air strike on a bread factory in the Aleppo district of Qadi Askar, according to activists.

The Free Syrian Army, which first took up arms against the Assad regime a year ago, is an alliance of loosely-connected brigades under the theoretical leadership of mid-ranking army defectors based mostly in Turkey.

"We are calling on the officers in Turkey to join the struggle," said one of the march's planners, who gave his name as Mohamed Qashush, a surname used by many protest organisers.

Ibrahim Qashush was an activist from the central city of Hama, scene of several massacres during the conflict, who wrote anti-Assad songs and organised the Syrian uprising's first demonstrations.

The man known as "the mocking bird of the revolution" was arrested and murdered in July last year by the security forces. His body was later found bearing signs of torture and with his vocal chords cut.

"We don't need anyone to sit in reception rooms in Paris and Istanbul for us and (FSA leader) Riad al-Asaad is top of the list. The revolution is in Syria," Mohamed Qashush said.