(Updates with statement from U.S. envoy, paragraphs 9 and 10)

The current influx of thousands of migrants attempting to cross into Greece from Turkey will soon see a significant spike, Turkish Interior Minister Süleyman Soylu said on Saturday.

More migrants will be able to move towards the border thanks to favourable weather conditions and increased Turkish security measures at the border to stem pushbacks, Yeniçağ newspaper quoted Soylu as saying at a press conference in the eastern province of Elazığ on Saturday.

"This is just the beginning. You should watch what will happen next. What has happened so far is nothing," Soylu said.

Thousands gathered at Turkey's border with Greece, after Turkish authorities said last week they would no longer stop migrants trying to get to Europe.

Turkey said the EU had failed to keep to pledges under a refugee deal signed in 2016, in which Ankara agreed to curb the flow of migrants and refugees into the EU in exchange for six billion euros for refugee-related services and visa-free travel in the EU for Turkish citizens.

More than 143,000 migrants have entered Greece as of Saturday, Soylu said, adding that warmer weather and a low discharge at the Meriç (Evros) River will allow for migrants to "easily walk through" the nearly 200-kilometre-long border with Greece.

"[Kyriakos] Mitsotakis does not have the ability to hold the border,’’ Soylu said.

Greek police have fired tear gas at refugees and migrants attempting to cross the border from Turkey while Athens on Saturday said nearly 600 people, aided by the Turkish army and the military police, threw tear gas canisters at the Greek side of the border overnight.

U.S .Special Envoy to the Western Balkans, Matthew Palmer, on Saturday defended Greece’s right to secure its land border with Turkey, calling the current situation “unsustainable'' and “unacceptable,” Kathimerini reported.

“The uncontrolled movement of thousands of people who have been misled into believing that the road to Europe is open is fundamentally destabilising, it’s unsustainable. It needs to change,” Palmer said.

The EU has condemned Turkey's policy and pledged 700 million euros ($ 777 million), half of it immediately, to help manage the migrant situation.