Their pleas to improve conditions at detention centers and camps housing more than 15,000 refugees and migrants on islands, activists said the Greek government has allowed many to pushed away.

Human Rights Watch said many who tried to unlawfully enter Greece from nearby Turkey, by a perilous sea route to the islands, or crossing a dangerous river on the northern land border, were forced back.

The group said it based its conclusions on the responses of 26 migrants in Greece as well as in Turkey, which has taken back only a relative handful under a swap deal with the European Union largely in limbo with Greece overwhelmed by asylum seekers.

The group said most of the alleged incidents occurred between April and November 2018 at the land border in northeastern Greece. It said interviewees reported hostile or violent behavior “by Greek police and unidentified forces wearing uniforms and masks.”

Greece has been repeatedly accused in recent years of so-called pushbacks — repulsing and returning to Turkey migrants entering illegally from that country. Successive governments have denied that.

The NGO said it interviewed asylum seekers and other migrants in Greece in May, and in October and November in Turkey who were from Afghanistan, Iraq, Morocco, Pakistan, Syria, Tunisia, and Yemen, and include families traveling with children. They described 24 incidents of forced deportations across the Evros River from Greece to Turkey.

“People who have not committed a crime are detained, beaten, and thrown out of Greece without any consideration for their rights or safety,” said Todor Gardos, Europe researcher at HRW.

“The Greek authorities should immediately investigate the repeated allegations of illegal pushbacks,” he said, Kathimerini reported.

According to the report, all of those interviewed reported “hostile or violent behavior” by Greek police and unidentified forces wearing uniforms and masks without recognizable insignia.

Twelve people said police or these unidentified forces accompanying the police stripped them of their possessions, including their money and personal identification, which were often destroyed.