Turkish authorities have stopped all citizens of Iraq, Syria and Yemen from flying from Turkey to Belarus, until further notice.
The Civil Aviation Authority of Turkey stated that it was due to illegal migrant crossings from Belarus into the European Union.
Belarus has been accused by the UN Security Council of using migrants to destabilise the EU’s eastern border.
The EU is urging Middle Eastern countries to take similar steps.
Alexander Lukashenko, Belarus’ authoritarian leader, has threatened to cut off gas supplies to Europe if new sanctions are imposed.
Meanwhile, paratroopers from Belarus and Russia have conducted joint exercises near the Polish and Lithuanian borders.
Russia, Belarus’s main ally, has rejected the EU’s accusations.
Thousands of people, many of them Kurds fleeing the Middle East, are camped near Poland’s border, braving subzero temperatures in the hope of entering the EU. The majority of the migrants are young men.
This week, crowds attempted to break through a barbed wire fence to enter Poland, only to be pushed back by Polish border guards and the army. Some migrants, however, have managed to sneak through.
Temperatures have dropped below freezing overnight, and at least seven people have died in recent weeks, many from hypothermia.
On Friday, Turkey barred Syrian, Yemeni, and Iraqi citizens from flying to the Belarussian capital, Minsk.
This could obstruct one of the routes used by migrants who, according to the EU, have been flown in by Belarus in order to create a deliberate humanitarian crisis on its border.
The EU accuses Belarus of fomenting the crisis by distributing Belarusian visas in the Middle East, flying in migrants, and encouraging them to attempt illegal border crossings.
Mr. Lukashenko denies this and claims that if the EU imposes a fifth round of sanctions, his country will be forced to respond.
According to the EU, he began luring migrants in retaliation for sanctions imposed for his brutal crackdown on protesters and critics. Last year, Belarusians took to the streets after he claimed a widely discredited election victory.
Iraq has stated that it will organise repatriation flights from Belarus for Iraqi nationals.
The EU is also reportedly considering sanctioning Russia’s state airline Aeroflot for allegedly transporting migrants to Belarus, which Aeroflot denies.
On Friday, Russia and Belarus held drills at the Gozhsky training ground. According to the Belarusian defence ministry, the drills included searching for and destroying enemy targets.
For the second day in a row, German Chancellor Angela Merkel met with Russian President Vladimir Putin to discuss the influx of migrants. In order to resolve the crisis, he has urged the EU to reestablish contact with Belarus.
Mr. Lukashenko’s threats to cut off gas supplies to Europe stoked new fears amid worsening natural gas shortages and rising European prices.
Belarus receives substantial transit fees for pipelines that transport Russian gas to the EU. Any decision would have to be approved by Russia, which is eager for the certification of its new Nord Stream 2 pipeline to Germany.