Russia’s military has carried out waves of air strikes in recent days on rebel-held areas of the southern Syrian city of Deraa, say anti-government fighters and witnesses.

Russian jets targeted rebel-held areas of Deraa for two days after Syrian opposition groups on Sunday stormed the heavily garrisoned Manshiya district in a campaign that sought to obstruct any army attempts to capture a strategic border crossing with Jordan from the opposition.

A rebel source said that there were at least 30 Russian sorties on Tuesday, thwarting further rebel gains in the heavily defended enclave that had allowed them so far to secure significant parts of the Manshiya.

“When the regime began to lose control of some areas … the Russian jets began their operations,” said Ibrahim Abdullah, a senior rebel commander.

Al Jazeera could not independently confirm the reported Russian assault.