Egyptian Foreign Minister Mohamed Kamal Amr said Syria should stop bloodshed on its own soil and called on it not to "violate the borders of neighboring states", warning of the "numerous dangers to the whole region" if the crisis spread.
Turkey hit back after what it called "the last straw" when the mortar bomb hit the Turkish border town of Akcakale on Wednesday, killing a mother, her three children and a female relative.
Turkish artillery hit targets inside Syria, killing several Syrian soldiers. NATO said it stood by member-nation Turkey and urged Syria to end "flagrant violations of international law."
Egypt's newly elected Islamist President Mohamed Mursi has been an outspoken critic of Syrian President Bashar al-Assad and has been building close ties with Turkey.
Arab League chief Nabil Elaraby offered condolences to Turkey over the mortar bomb which he said was "a serious threat to the peace and security in the region". (Reporting by Ayman Samir and Omar Fahmy; Writing by Yasmine Saleh; Editing by Robin Pomeroy)
