Ankara, March 4 -- Turkey said that NATO air defences destroyed an Iranian ballistic missile headed into Turkish airspace on Wednesday, marking the first time the alliance member has been drawn into the Middle East conflict and raising the possibility of a major expansion involving its bloc allies.

Turkey - Iran's neighbour that had sought to mediate U.S.-Iran talks before the air war that began at the weekend - warned "all parties to refrain from actions that would lead to further escalation," suggesting it was not poised to call upon the trans-Atlantic defence bloc for support.

But Ankara could potentially invoke NATO's Article 4 after the airspace breach if it deemed the threat serious enough, a step that could lead to the alliance's...