A human rights group says German Chancellor Angela Merkel and top European Union officials should rethink the EU's refugee deal with Turkey, as they travel to the Syrian border to promote the troubled agreement.

Saturday's trip to the Turkish border city of Gaziantep, including a refugee camp, comes amid questions over the legality of the March 20 EU-Turkey deal to deport migrants who do not qualify for asylum in Greece back to Turkey.

Human Right Watch acting director Judith Sunderland says instead of touring a "sanitized" refugee camp, the EU leaders should focus on the tens of thousands of Syrians blocked at the border. She also urged them to visit a detention center for migrants "abusively deported from Greece."

Sunderland says "that should make them rethink the flawed EU-Turkey deal."