One such incident, noted by the Berlin combat support ship on June 19, was confirmed by the German government in response to a parliamentary question.

Lawmaker Andrej Hunko had asked whether the crews of German ships or aircraft in the Aegean Sea had observed refugees being prevented from continuing their journey by the Greek coastguard or EU border agency Frontex, or had been “forced back into Turkish waters.”

“The German government is in constant contact with the Greek government and draws attention to the provisions of international law in force,” the government said.

Its statement implied that the June 19 incident had not been the first, while sources confirmed the two other incidents to dpa on condition of anonymity.

“The European Union must immediately comment on the incidents now documented by the German government,” said Hunko, a representative for the hard-left party Die Linke.

He called for Frontex missions in Greece to be abandoned because the Greek government was not observing the European Convention on Human Rights, under which states are not allowed to push back boats from European territories.

In response to reports on social media about a similar incident south of the island of Lesbos last weekend, the Greek coastguard said, “We are not aware of anything.”