Syrian rebels on Sunday launched a surprise attack on Baba Amr, a former rebel stronghold in the central city of Homs, a year after it was captured by the army in a bloody battle, a monitoring group said.

"At dawn, the rebels launched a surprise attack on Baba Amr, which they have entered," Syrian Observatory for Human Rights director Rami Abdel Rahman, who was in contact with the rebels, told AFP.

Baba Amr gained notoriety when hundreds of Syrians were killed last year during more than a month of army bombardment and combat with the outgunned rebels, who were finally driven out by troops loyal to President Bashar al-Assad.

Reflecting its importance to the regime, Assad visited the devastated district on March 27 to mark the "victory" of his troops, and made promises broadcast on state television that Baba Amr would rise again and return to "normal life."

As well as those killed there, dozens of bodies were found in neighbouring districts of Homs, and included those of people fleeing the fighting in Baba Amr, according to the Observatory.

Two foreign journalists, American reporter Marie Colvin of The Sunday Times in Britain and French photojournalist Remi Ochlik, were among those killed in the fighting when a makeshift media centre in Baba Amr was shelled by Syrian forces.