[Migrants are escorted by police officers as they disembark from a ferry at a port in the Turkish coastal town of Dikili]BRUSSELS (Reuters) - The European Union said it was confident its cooperation with Turkey on migration will continue to hold firm, a spokeswoman for the bloc said on Friday. Turkey's foreign minister said earlier in the day that Ankara could cancel a bilateral deal with Athens on returning migrants from Greece to Turkey, a key element of the broader EU-Turkey deal on migration. (Reporting by Jan Strupczewski and Gabriela Baczynska; Editing by Alissa de Carbonnel)