Perilously close to Turkish soil, the sound of mortars, bombs and gunfire echoes through the Syrian border town of Ras al-Ain.

It's the fourth day of air strikes on the city as the pro-Assad military battles to recapture the area, seized by the Free Syrian Army last Thursday.

A Syrian jet struck twice before circling and dropping more bombs, rocking buildings on the Turkish side of the frontier and sending huge plumes of smoke over Ras al-Ain.

Several people, mostly women and children, rush across the border seeking shelter in neighbouring towns.

Turkey is reluctant to be drawn into a regional conflict, but the proximity of the bombing raids to the border is testing its pledge to defend itself from any violation of its territory.