berlin germany foreign ministry warn citizens travel turkey risk arbitrary detention even tourist areas revise travel advice spate arrest german citizens consider politically motivate change travel advice issue tuesday mark new low relations nato ally blow tourist sector already hit militant attack fall-out last year fail coup attempt turkey trigger sharpen travel advice detention coastal antalya airport last week two germans one since release berlin believe like 11 others detain political reason risk similar detentions part turkey include tourist regions new advice read fall short formal travel warn issue war-afflicted countries like afghanistan iraq yemen would make obtain travel insurance hard take tourists decision whether travel foreign minister sigmar gabriel say describe detail aware go large number european citizens catch crackdown follow last year fail coup president tayyip erdogan wake tens thousands turks imprison terrorism charge critics say crackdown amount undiscriminating purge erdogan opponents germany warn turkey travel spate arrest