EU migration commissioner Dimitris Avramopoulos said on Thursday there was an urgent need to stop illegal departures from Turkey as Greece struggled to cope with a sharp rise in refugee arrivals.
"Irregular arrivals to Greece increased over the past weeks and months," Mr Avramopoulos said in Ankara, standing alongside the Turkish and German interior ministers.
"There is an urgent need to further strengthen the prevention and detection of irregular departures from Turkey."
The UN refugee agency announced on Tuesday that arrivals by sea from Turkey to Greece, mostly of Afghan and Syrian families, increased to 10,258 in September.
That represented the highest monthly total since the 2016 deal between Turkey and the EU to curb the flow of arrivals, the refugee agency said.
But Turkish Interior Minister, Suleyman Soylu, called on the EU to share the refugee burden as Ankara feared a new influx from Syria's Idlib province, near the border.
Turkey "has fulfilled its commitments" under the 2016 accord with the EU, Mr Soylu said.
"We expect Europe to be in the same frame."
He warned that the hostilities in Idlib could spark mass movement into Turkey, which is already home to 3.6 million Syrian refugees.
Mr Avramopoulos said he appreciated the work already done by Ankara.
"Our joint visit is proof of our continued co-operation with Turkey on managing migration together, as partners," he said.
German Interior Minister Horst Seehofer and Mr Avramopoulos are due to visit Greece on Friday.
Mr Seehofer said Europe was ready to help Turkey.
"Wherever we can make a contribution we are willing to do so," he said.
Turkish President Recep Tayyip Erdogan threatened last month to "open the gates" and allow Syrian refugees to leave Turkey for western countries if plans with the US to establish a safe zone to resettle them in northern Syria failed.
"We cannot be forced to handle the burden alone," Mr Erdogan said.
