Amnesty International said Turkey has forcibly returned hundreds of Syrian refugees to their homeland since mid-January.
It said this practice exposes “fatal flaws” in an agreement between Turkey and the European Union.
The organisation said its research on the Turkish-Syrian border suggests that around 100 Syrians – who often have not registered in Turkey – are expelled from Turkey each day.
Advocacy groups are concerned that the deal, which aims to stem the flow of illegal migrants and goes into effect on , threatens the rights of asylum seekers, and they question whether Turkey is a safe country for them. The EU-Turkey deal stipulates the return to Turkey of any Syrian refugee arriving on the Greek islands, to be offset by resettling a Turkey-based Syrian in the EU.
“Far from pressuring Turkey to improve the protection it offers Syrian refugees, the EU is in fact incentivising the opposite,” said John Dalhuisen, Amnesty International’s director for Europe and Central Asia.
“Having witnessed the creation of Fortress Europe, we are now seeing the copycat construction of Fortress Turkey.
In earlier stages of the conflict, Syrians who held passports were able to cross at regular border gates and even those who entered illegally could register with the authorities. Now only those needing urgent medical care are allowed to enter and there are an estimated 200,000 displaced Syrians within 12.4 miles of Turkey’s border.
Tightened border restrictions and new visa requirements for Syrians, the organisation said, have also pushed Syrians into the arms of smugglers who charge an average of $1,000 (£705) per crossing.
Amnesty said Turkish of authorities have scaled back the registration of Syrian refugees in the south which makes it impossible for them to access basic services.
Turkey has taken in 2.7 million Syrian refugees since the civil war began five years ago.
The Turkish foreign ministry said it had maintained an “open door” policy for Syrian migrants and strictly abided by the principle of not returning people to a country where they are liable to face persecution.
A spokesman said: “None of the Syrians that have demanded protection from our country are being sent back to their country by force, in line with international and national law.”