Europe's border agency Frontex routinely covered up illegal "pushbacks" of migrants by the Greek coastguard, media reports said Thursday.
The reports cited a leaked internal review.
A 129-page investigation by the European Anti-Fraud Office (OLAF) found that Frontex, under former executive director Fabrice Leggeri, was complicit in Greek efforts to force migrants and asylum-seekers crossing the Aegean Sea to return to Türkiye, German magazine Der Spiegel wrote.
The confidential report was also seen by France's Le Monde newspaper and investigative outfit Lighthouse Reports. It follows repeated allegations by aid groups that Frontex was turning a blind eye to Greek human rights violations at sea.
"Instead of preventing the pushbacks, Leggeri and his people covered them up. They lied to the EU Parliament and concealed the fact that the agency even supported some pushbacks with European taxpayers' money," Der Spiegel wrote.
The OLAF review found that at least six pushbacks involved Greek coastguard ships that had been co-financed by Frontex, the magazine said.
In one incident in August 2020, Frontex Surveillance Aircraft filmed the Greek coastguard towing a dinghy with around 30 migrants on board towards Turkish waters -- when they should have been taken to Greece.
Instead of confronting Greek authorities, Frontex stopped patrolling the Aegean by air, saying the planes were needed elsewhere, Der Spiegel wrote.
A hand-written note found later by OLAF investigators said that Frontex management withdrew the aircraft "so as not to become a witness" to Greece's illegal actions.
The Greek government has consistently denied the allegations of pushbacks.
Greek migration minister Notis Mitarachi told journalists on Thursday: "I haven't read the report. I have read the summary.
"The summary does not blame Greece directly for any wrongdoing. We have the right to protect our borders. The EU has a right to protect the external borders."
Visiting Frontex offices on an official trip to Athens, German Foreign Minister Annalena Baerbock said: "Even if I clearly cannot verify in detail what happened in each individual case... there have been pushbacks that are incompatible with European law".
She stressed "measures have been taken immediately".
"We have all talked about it today, in order to have more human rights observers on the spot", she added.
The OLAF investigation paints a damning picture of Leggeri's leadership, Spiegel said, adding that the report's revelations played a role in his resignation last April.
Responding to the OLAF report leak, a European Commission spokeswoman said "a set of measures" had already been introduced "to address the governance issue of Frontex", which has been headed by interim executive director Aija Kalnaja since the start of July.
"In terms of our work with the Greek authorities, there is progress also on the ground," European Commission spokeswoman Anitta Hipper told reporters, pointing to a new legislative proposal "to ensure that there is a robust monitoring system" for arriving migrants.
Former boss Leggeri's seven years as Frontex chief, marked by repeated political scares over migrant arrivals in Europe, coincided with a major increase in resources for the agency.
Frontex is set to grow to 10,000 staff watching the EU's external borders by 2027.
