Thousands of migrants and refugees from Turkey are attempting to enter Greece after Ankara announced it could no longer enforce a 2016 deal with the EU to prevent migrants entering Europe.
Turkey has said it will not prevent migrants on its territory from reaching Europe, triggering an almost instant rush to the borders it shares with European Union member Greece after the Syrian conflict escalated.
The International Organisation for Migration put the number of people along the Greece-Turkey border at 13,000.
A young boy died when a boat capsized off the Greek island of Lesbos on Monday, Greek police said, the first reported fatality since Turkey opened its borders last week.
Nearly a million Syrians have fled to the Syrian-Turkish border since December, amid heavy fighting in the Idlib region between Turkish-backed rebels and Syrian government forces.
Turkey has an estimated 3.7 million Syrian refugees, as well as migrants from other countries – but previously stopped them from entering Europe.
The deal was proposed as a solution to the migrant crisis in 2015 where almost one million refugees and migrants arrived in the EU.
Hundreds of thousands of people fled to escape the wars in Syria and Afghanistan.
On Monday, a senior Turkish official told the Reuters news agency: “We have decided, effectively immediately, not to stop Syrian refugees from reaching Europe by land or sea.
"All refugees, including Syrians, are now welcome to cross into the European Union."
The prospect of a new migration crisis caused alarm in European countries already contemplating restrictions on internal borders and public gatherings to fight the coronavirus.
Greece, a European Union member state neighbouring Turkey, vowed not to admit the migrants and responded to the incoming refugees at its border.
Greek police fired tear gas toward migrants who were gathered on its border with Turkey and demanding entry on Saturday.
In addition to some 3.7 million Syrian refugees, Turkey also hosts migrants from Afghanistan, Iran and Morocco, among others.