Israel stepped up airstrikes on Syria, declaring the attacks a warning to the new Islamist rulers in Damascus as it accused their ally Turkey on Thursday of trying to turn the country into a Turkish protectorate.

The Syrian government has condemned Israel's "impunity" as Israel stepped up air strikes on Syria, with jets hitting military targets, including an airport. Wednesday's attacks, which included ground incursions, killed 13 people, with Israel claiming it was responding to fire from gunmen during an operation in the south.

Israel defended the moves as necessary security measures, but Syria accused it of trying to destabilize the country.