* Eighteen staff withdrawn to Kuwait * Precaution after storming of Mosul consulate * Forty-nine Turks still held by militants (Recasts with Basra consulate evacuation) ANKARA, June 17 (Reuters) - Turkey evacuated its consulate in the southern Iraqi city of Basra on Tuesday, less than a week after its mission in the **rthern city of Mosul was overrun by militants who seized diplomats, soldiers and children. Foreign Minister Ahmet Davutoglu said on his Twitter account that the Basra staff had been evacuated to Kuwait due to an increased security risk.