Migrants and left wing, German agitators have been demonstrating the “shameful” European Union (EU) plan to send “irregular” migrants back to Turkey, which came into effect today.

“If they make me go back to Turkey I’ll throw myself and my family into the sea,” Mr. Mustafa, a Syrian waiting with his wife and children at the port of Chios island told Greek news agency ANA. “We went from hell to hell”, he said.

The deportation began this morning, with a group of Pakistani men with little or no chance of being granted asylum in Europe being returned the short distance across the Aegean on a small Ferry.

In the preceding days migrants have repeatedly broken out of the new holding centers on the Greek islands, and some have even threatened to kill themselves if returned to turkey.

Others near the border with Macedonia—which is now firmly closed—have formed human chains to block major roads in protest.

In late March, Ankara and Brussels agreed to close the so-called Balkan route by which over a million migrants traveled through Greece and Macedonia north to the other EU member states during the past year.

According to the agreement, in exchange for financial and political favours Turkey pledged to take back all the illegal migrants who cross into the European Union from its borders.

Brussels will provide 3 billion euros in aid to Ankara for the more than 2 million Syrian refugees residing in Turkey, with the option to increase aid by an additional 3 billion. Turkey also expects an accelerated process of accession to the EU, one of its long-standing goals.

The deal has faced strong opposition from rights groups, and senior UN migration official Peter Sutherland said Saturday that the deal was “absolutely” illegal.

“Collective deportations without having regard to the individual rights of those who claim to be refugees are illegal,” he told BBC radio. “Their rights have to be absolutely protected where they are deported to — in other words Turkey.”

Amnesty International said this week that Turkey was not a “safe country” for refugees, reporting that Ankara was forcing around 100 Syrians to return to their war-torn country every day.

Turkey rejected the criticism, with the foreign ministry saying Saturday “the allegations do not reflect reality in any way”.

Tom Williams contributed to this report