Greece has informed Turkish authorities about reports of migrants stranded on an islet in the Evros border river, the Greek migration minister has said.

But Notis Mitarachi said nobody had been found on the islet -- adding it was "outside Greek territory".

NGOs and local media reported that dozens of people had been trapped on the island on the northern border with Turkey for several days.

On Saturday, the UN refugee agency UNHCR tweeted: "We continue to be gravely concerned for the safety and wellbeing of some 40 people allegedly stranded on an islet at the Greece-Turkiye border.

"According to reports received a child has tragically already died. Unless urgent action is taken, we fear further lives remain at stake."

Mitarachi wrote on Twitter on Sunday: "we conducted repeated searches, with suitable technical means, without detecting any human presence in the islet.

"It has been confirmed that this is a point outside Greek territory so immediately we notified Turkish authorities."

Following "published articles about the presence of migrants on an islet in Evros", Greek police said they had informed Turkish border authorities about the case "twice" in recent days.

Greece has repeatedly been accused of illegally turning migrants back to Turkey at Evros and in the Aegean Sea. Athens denies the accusations.

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