By Dasha Afanasieva and Tulay Karadeniz

ANKARA (Reuters) – Turkey has illegally returned thousands of Syrians to their war-torn homeland in recent months, highlighting dangers for migrants sent back from Europe under a deal due to take effect next week, Amnesty International said on Friday.

Turkey agreed with the EU this month to take back all migrants and refugees who cross illegally to Greece in exchange for financial aid, faster visa-free travel for Turks and slightly accelerated EU membership talks.

But the legality of the deal hinges on Turkey being a safe country of asylum, which the rights group said in a report was not the case. Amnesty said it was likely that several thousand refugees had been sent back to Syria in the past seven to nine weeks, flouting Turkish, EU and international law.

Turkey’s foreign ministry denied Syrians were being sent back against their will, while a spokesman for the European Commission said it took the allegations seriously and would raise them with Ankara.

Separately, the U.N. refugee agency UNHCR said it had asked for access to Syrians returned to Turkey from Greece “to ensure people can benefit from effective international protection and to prevent risk of refoulement”, referring to unlawful deportations of refugees at risk of persecution.

Ankara said it had maintained an open-door policy for Syrian migrants for five years and strictly abided by the “non-refoulement” principle.

“None of the Syrians that have demanded protection from our country are being sent back to their country by force,” a foreign ministry official told Reuters.

But Amnesty said testimonies it had gathered in Turkey’s southern border provinces suggested authorities had been rounding up and expelling groups of around 100 Syrian men, women and children almost daily since the middle of January.

“In their desperation to seal their borders, EU leaders have wilfully ignored the simplest of facts: Turkey is not a safe country for Syrian refugees and is getting less safe by the day,” said John Dalhuisen, Amnesty International’s director for Europe and Central Asia.

Under the deal, Turkey is supposed to be taking in migrants returned from Greece on April 4, but uncertainty remains over how many will be sent back, how they will be processed, and where they will be housed.

The aim is to close the main route by which a million migrants and refugees crossed the Aegean Sea to Greece in the last year before heading north, mainly to Germany and Sweden.

(Additional reporting by Gabriela Baczynska in Brussels and Stephanie Nebehay in Geneva; Editing by Nick Tattersall and John Stonestreet)