Denmark is also to offer one of its surveillance aircraft to the EU’s border control agency Frontex to assist in light of the changing circumstances around the Greek-Turkish border, Ritzau reports.

Turkey’s president, Recep Tayyip Erdogan on Saturday opened both the overland border and the sea route between Turkey and the EU. That includes borders with both Greece and Bulgaria.

The PM said she was concerned about a potential increase in refugee and migrant arrivals in the EU as a result of the Turkish decision.

“There’s no doubt that Greece and Bulgaria face a big job in protecting Europe’s outer border,” she said.

“I have therefore contacted my Greek and Bulgarian colleagues and given notice that Denmark is ready to provide support with contributions that can protect Europe’s borders,” she said.

Frederiksen has written to Greek PM Kyriakos Mitsotakis and Bulgarian PM Boyko Borissov.

In the letter to Mitsotakis, she called the situation faced by Greece “extremely difficult” and the burden on the EU country “unacceptable”, Ritzau reports.

The Danish Challenger surveillance aircraft offered to Frontex would assist with the agency’s efforts against irregular migration and cross-border crime in the Mediterranean region.

Thousands of people have attempted to cross into Greece since Erdogan’s decision to open borders on Saturday. Greece has so far denied the migrants entry.

According to a UN estimate, up to 13,000 people are currently stranded at Greece’s border with Turkey.

EU Commission president Ursula von der Leyen has promised the Greeks assistance, while Denmark’s foreign minister Jeppe Kofod has said the country “would not accept” a repeat of the situation in late 2015, when there was a peak in refugee arrivals in Europe from conflict zones such as Syria.

“Protection of the EU’s outer border is an important priority for the government. That’s why we have reacted quickly and reached out to both Greece and Bulgaria,” Kofod said.

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