Migrants sit waiting near the buffer zone at the Turkey-Greece border in Pazarkule, Edirne Province, Turkey on Saturday. Thousands of migrants stuck at the border clashed with Greek police on Saturday. Photo: AFP

The EU's border protection agency Frontex said Sunday it is on "high alert" at borders with Turkey as thousands of migrants seek to enter the bloc, adding it is deploying support to Greece.

"We... have raised the alert level for all borders with Turkey to high," the Frontex spokeswoman said in a statement to AFP, adding: "We have received a request from Greece for additional support. We have already taken steps to redeploy to Greece technical equipment and additional officers."

Greece has blocked nearly 10,000 migrants trying to enter from the Turkish border over the past 24 hours, a Greek government source said Sunday.

A massive influx of migrants swelled along the border over the weekend after Turkey's President Recep Tayyip Erdogan threatened to open its frontier to Europe. 

He is seeking to pressure EU governments over the Syrian conflict after an airstrike in Syria's Idlib province on Thursday killed dozens of Turkish soldiers.

A Greek government source said Sunday its army and police had stopped thousands from entering its territory. 

Huge crowds tried to cross into Greece via the Kastanies Forest in the early Sunday, the source said. 

Greek authorities said 73 migrants had been arrested, but added that they "weren't from Idlib, but from Afghanistan, Pakistan, Somalia."

Some 13,000 migrants have gathered along the Turkey-Greece border, including families with young children, the International Organization for Migration said Saturday.

Reuters