BERLIN/AMSTERDAM- Germany and the Netherlands revised travel advice for Turkey this week amid a deepening row over European cancellations of events by Turkish officials aimed at rallying support for a vote to expand the powers of Turkish President Tayyip Erdogan.The Dutch foreign ministry urged citizens visiting Turkey to exercise caution in revised travel advice issued late on Sunday."There have been diplomatic tensions between Turkey and the Netherlands," the ministry wrote. "Be alert and avoid large crowds."The German foreign ministry, in an updated notice posted on its website on Monday, said travelers should expect heightened tensions and protests ahead of the April 16 referendum."Travelers are therefore advised to stay away from political rallies and large crowds," the ministry said. It had previously advised citizens about heightened security risks in Turkey following last year's failed coup attempt.