German business warns Turkey trade to plunge amid row

German business groups warned Thursday that economic ties with Turkey would go from bad to worse as a sharply escalating diplomatic row heightens uncertainty.

The biggest EU economy, home to three million people of Turkish origin, has repeatedly clashed with President Recep Tayyip Erdogan over civil rights and other issues, especially since a failed coup attempt a year ago sparked mass arrests.

After Turkey remanded in custody several human rights activists, Foreign Minister Sigmar Gabriel said that Germany -- Turkey's top trading partner, number-two foreign investor and biggest source of tourists -- would launch a sweeping overhaul of bilateral relations.

German holiday-makers were urged to exercise "heightened caution" in Turkey, and Gabriel said Berlin would review investment aid and state guarantees and discourage German companies from doing business there.