German Chancellor Angela Merkel and top European Union officials are travelling close to Turkey's border with Syria on Saturday in a bid to bolster the troubled agreement on migrant deportation.
Human-rights groups are criticising the trip to what they call a "sanitised" refugee camp and say EU officials should look further at the tens of thousands of Syrian refugees now blocked from entering Turkey.
The German leader is also facing pressure to speak out against freedom-of-speech restrictions in Turkey.
The trip to the border city of Gaziantep by Ms Merkel, EU Council president Donald Tusk, EU Commission vice president Frans Timmermans and Turkish prime minister Ahmet Davutoglu comes as many have questioned the legality of the March 20 EU-Turkey deal allowing for the deportation of migrants who do not qualify for asylum in Greece back to Turkey.
The EU in return has earmarked six billion euros to Turkey over the next four years to help improve conditions for the 2.7 million Syrian refugees inside Turkey. The EU is also set to allow visa-free travel to Turkish citizens.
Rights groups, EU legislators and the UN refugee agency have questioned the moral and legal implications of expelling people from Greece back to Turkey — a country that many consider unsafe on grounds of security and human rights.
Despite insisting it has an open-door policy for Syrian refugees, Turkey in the past few months has blocked several thousand refugees who were fleeing northern Syria at the border, providing aid to them at displaced persons camps near the border instead.
Human-rights groups say some of the camps have been attacked and are pressing Ankara to give the refugees shelter inside Turkey.
Amnesty International says Turkish authorities have also for the past three months been expelling about 100 Syrians a day back to war-ravaged Syria — an accusation Turkey has denied.
The New York-based advocacy group Human Rights Watch has urged the EU leaders to understand the whole refugee picture at the Turkish border.
"Instead of touring a sanitised refugee camp, EU leaders should look over the top of Turkey's new border wall to see the tens of thousands of war-weary Syrian refugees blocked on the other side," said Judith Sunderland, Human Rights Watch's acting deputy Europe and Central Asia director.
“Then, they should go to the (Turkish) detention centre for people who were abusively deported from Greece. That should make them rethink the flawed EU-Turkey deal.”
Ms Merkel's visit also comes as controversy over her decision to grant Turkey's request to let German prosecutors and courts decide whether German comedian Jan Boehmermann had insulted Turkish president Recep Tayyip Erdogan.
Critics have accused Ms Merkel of kowtowing to Turkey because of the country’s important role in stopping the influx of migrants to Europe.
Turkey’s leaders, meanwhile, are warning that the whole migrant deportation deal will collapse if the EU fails to grant Turkish citizens the right to visa-free stays for tourism or business by July.