The Greek government is detaining migrants in secret at an extrajudicial location before expelling them to Turkey without due process, as part of several hardline measures to seal its border, contravening international law.

According to a report from the New York Times, several migrants have reported having been captured, stripped of their belongings, beaten and expelled from Greece without being given a chance to claim asylum or speak to a lawyer, in an illegal process known in international law as refoulement.

"The extrajudicial center is one of several tactics Greece is using to prevent a repeat of the 2015 migration crisis," the online report said.

The Greek government did not immediately respond to a request for comment. Athens has always denied sending people back to Turkey without due process.

The Times said it had confirmed the existence of the site through reporting and forensic analysis of satellite imagery.

It also interviewed a Syrian man who claimed to have been taken to the site, near the border village of Poros.

Agence France-Presse (AFP) teams in the area at the time saw soldiers boarding migrants onto military vehicles. Other unmarked vans were also picking up migrants wandering the streets.

When asked last week about the fate of migrants caught after crossing the Evros river into Greece, the migration ministry declined to comment.

Greek locals and people who have spent time on the border have confirmed the illegal practice.

Meanwhile, Turkish officials said that at least three migrants had been shot and killed while trying to enter Greece in the past two weeks.

The Greek government has defended its actions as a legitimate response to recent provocations by the Turkish authorities, who have allowed migrants to leave its borders for Europe in light of a recent influx from those fleeing war-torn Idlib, where Turkey has recently restored order after a prolonged attempt by the Assad regime to encroach upon the de-escalation zone established by Turkey in partnership with Russia.

Greek authorities have denied reports of deaths along the border. Meanwhile, former U.N. Special Rapporteur on migrant human rights, François Crépeau, said it was the equivalent of a domestic "black site."

As reported widely in both the Turkish and international press, the Greek Coast Guard, nominally a lifesaving institution, has fired shots in the direction of migrants on board dinghies trying to reach Greek shores in recent weeks.

One migrant, speaking to the New York Times, said of the Greek border guards: "To them, we are like animals," having spent a night detained, without food or drink, before being ferried back across the border dividing Turkey and Greece.

Turkey currently hosts some 3.6 million Syrian refugees, more than any other country in the world. Ankara has so far spent $40 billion on the refugees, according to official figures. Ankara has frequently criticized the lack of financial and humanitarian support from the international community for refugees living in the country and has warned the European countries about new possibilities of migration waves. Ankara has also repeatedly complained that Europe has failed to keep its promises under the 2016 EU-Turkey refugee deal to help migrants and stem further migrant waves.

As a response to the lack of humanitarian and financial aid from the international community, Erdoğan warned European countries that Turkey could not handle a new migration wave and will have to open the doors of its borders, allowing a refugee influx toward Europe.

The latest humanitarian crisis in northwestern Syria's Idlib caused by Assad regime attacks has forced nearly 1 million people to move near the Turkish border for refuge. As a result, Turkish officials announced that they would no longer try to stop migrants from reaching Europe. Since then, thousands of migrants and asylum seekers have flocked to the Turkish province of Edirne along the border with Greece and Bulgaria to make their way into Europe.

The Greek reaction to the migrants has been harsh, with many battered, attacked or tear-gassed, and several killed by Greek forces. Greek forces have even tried to sink the rubber boats of refugees trying to cross the Aegean.