Turkey 'can't take' new migrant wave from Afghanistan
"A new wave of migration is inevitable if the necessary measures are not taken in Afghanistan and in Iran," Erdogan said during a telephone call with German Chancellor Angela Merkel.
"Turkey, which already has five million refugees, cannot take an additional burden of migrants," he told Merkel.
Erdogan made similar comments to Greek Prime Minister Kyriakos Mitsotakis on Friday.
Erdogan also accused Brussels of being "evasive" with regard to Ankara's request to revise a 2016 deal between Turkey and the European Union aimed at stemming flows of would-be refugees.
Signed in 2015 during the EU's migrant crisis, the accord allows "irregular" migrants reaching the Greek islands to be returned to Turkey in exchange for aid.
The EU also pledged to work with Ankara on upgrading an existing customs union and on paving the way for Turkey's eventual accession to the bloc.
Turkey further wants visa-free travel to EU nations and the resumption of regular summits between the two sides.
But Ankara has regularly accused the EU of not keeping to the terms of the accord.
Merkel's office, for its part, responded by saying that the evacuation of people from Afghanistan remains "the top priority".
The two leaders agreed to "close cooperation to support the work of international organisations, in particular UN refugee aid agencies, in Afghanistan and in neighbouring countries," said a spokeswoman for Merkel.