ISTANBUL — Hundreds of people in Istanbul marched to the Greek consulate on Saturday to protest the deaths of 19 migrants near Turkey’s border with Greece.

Turkish authorities said they froze to death earlier this week after being illegally pushed back across the border by Greek guards. Athens has strongly rejected the accusation.

The demonstration, organized by Turkish humanitarian groups, saw about 300 protesters walk to the consulate near one of Istanbul’s main shopping streets behind a banner reading “Close borders to racism, open to humanity.” Dozens of riot police stood by as aid workers addressed the crowd.

“People were stripped of their clothes and their belongings were taken. They were left to die and the whole world remains silent about this,” said Fehmi Bulent Yildirim, chairman of IHH, a humanitarian aid group.

He called on the European Parliament to “take action on this issue as soon as possible and stop this cruel attitude that commits these crimes against humanity.”

Kenan Alpay, vice chairman of humanitarian group Ozgur-Der, said the pushbacks showed “brutality beyond hypocrisy.” He added: “We invite the Greek government to abandon these ugly policies.”

Turkey has frequently alleged that Greece carries out pushbacks of migrants seeking to cross the northwestern land border or trying to reach Greece’s Aegean islands on inflatable dinghys.

In an interview with broadcaster AHaber on Friday, Vice President Fuat Oktay accused Greece of “murder,” adding that “all EU countries, unfortunately, are responsible for the deaths of 19 people.”

Turkish President Recep Tayyip Erdogan has pledged to raise the alleged ill-treatment of migrants by Greece during his meetings with world leaders.

Greece’s Migration Minister Notis Mitarachi has described the deaths as a “tragedy” but strongly denied the claim that Greek forces had pushed back the migrants, insisting that the migrants never made it to the border.

Turkey is a major crossing point for migrants from the Middle East, Asia and Africa seeking a better life in EU countries, with most crossing into Greece.

The EU, which saw 1 million mostly Syrian refugees enter its territory in 2015, signed a migration agreement with Turkey in 2016 that has seen the flow of people dramatically reduced.