The Greek government came under fire after a video showing alleged pushback of irregular migrants by its coastguard units in the Aegean Sea on Friday.

The footage, published by the New York Times, has sparked calls by the U.N. High Commissioner for Human Rights for an independent probe.

It also comes two days before a general election in which conservative Prime Minister Kyriakos Mitsotakis is facing a challenge from leftist predecessor Alexis Tsipras.

A tough stance against immigration is a key plank of Mitsotakis's election platform. Earlier in the campaign, the prime minister traveled to the land border with Turkey where he vowed to extend a 5-metre-high steel fence to contain the inward migration flow.

The footage in question was shot by a human rights activist on Lesbos last month.

In it, a group of irregular migrants, including a baby, are driven in a white van to a "small cove spot with a wooden dock at the southern tip" of the island where they are taken out to the Aegean waters on a speedboat.

The migrants are then put on "a black inflatable life raft and set adrift," the New York Times wrote, adding that about an hour or so later, Turkish coast guard boats arrived to rescue them.

The report added that this was the April 11 rescue of "12 irregular migrants on the lifeboat that was pushed back to Turkish territorial waters by Greek assets", which Turkish coast guards had documented in a statement.

The New York Times said it had tracked down the migrants at the Izmir detention facility where they recounted their ordeal.

Contacted by AFP, Greece's migration ministry declined to comment.

But the U.N. High Commissioner for Human Rights has described the footage as "disturbing" and called for an investigation and closer monitoring of the border area.

"Everyone has the right to be protected from such treatment," said Ravina Shamdasani, spokeswoman for the commissioner. "An independent, effective investigation is crucial."

"We remain seriously concerned about continued and systematic pushbacks at the Greece-Turkey border, which violate the prohibition of collective expulsions and the principle of non-refoulement," she added.

The commissioner backed "establishing an independent and effective border monitoring mechanism that would investigate allegations of violence at borders in collaboration with civil society", she said.

While the Turkish coast guard has come to the rescue of thousands sent back by Greek authorities, countless others died at sea as boats full of refugees sank or capsized, especially in the Aegean Sea where both countries share a border.

Barely a month into 2023, Greece’s mistreatment of asylum-seekers reached double digits.

A report by Türkiye’s Ombudsman Institution said in July 2022 that Greece has pushed back over 42,000 migrants since 2020.

Between Jan. 1 and Dec. 16, 2022, the Turkish Coast Guard Command’s Aegean Command Station saved 47,498 irregular migrants in 1,550 separate cases across its areas of responsibility, over 18,000 of whom were victims of Greece’s pushback policy.

Athens consistently denies the accusations despite abundant migrant testimonies, media evidence and international scrutiny. Prime Minister Kyriakos Mitsotakis’ government since coming into office in 2019 has vowed to make his country "less attractive" to asylum-seekers.

The migrant crisis in the Aegean and the broader Mediterranean remains unsolved.