Turkey faces a long and arduous path to obtaining visa-free travel within the European Union, and immediate prospects are not bright, Germany's European affairs minister said on Tuesday.Michael Roth told Reuters that it was clear from the start that a migrant deal struck between the EU and Turkey required completion of 72 criteria before Turks could be granted visa-free travel."Turkey faces a very long and difficult path. The criteria must be fulfilled, and it doesn't look good at the moment," Roth said. "As long as the 72 criteria have not been fulfilled - and a few are still open - there cannot be visa liberalization."At the same time, Roth said it was important to keep open channels of communication with Turkey, which would remain an important partner given the refugee crisis, and because of the presence of over 3 million people in Germany of Turkish descent.