Greek police have fired tear gas at refugees and migrants attempting to cross the border from Turkey, in the latest incident since Ankara declared its borders with the European Union open.

Saturday's unrest also saw tear gas coming from Turkish territory and being fired towards Greek police near the crossing at the Pazarkule border, known as Kastanies on the Greek side, according to reports.

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Meanwhile, hundreds of people could be seen on the Turkish side of the high perimeter fence, with some pushing at it.

A Greek government statement issued 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.

There were several attempts to breach the border fence, and fires were lit in an attempt to damage the barrier, the statement said.

Sea crossings

The development came after Turkish President Recep Tayyip Erdogan ordered the coastguard to prevent migrants crossing the Aegean Sea because of the risks.

"On the orders of the president ... permission will not be given for migrants to cross the Aegean Sea because it is dangerous," the coastguard tweeted on Friday.

"The approach of not intervening against migrants wishing to leave Turkey remains in practice but this [new] approach covers sea crossings because of the dangers," it added in another tweet.

The coastguard said 97 migrants were rescued on Thursday after "the Greek side flattened three boats and left them in a half-sinking state in the middle of the sea".

The instruction comes after Erdogan said last month that refugees and migrants would not be prevented by Turkish authorities from leaving Turkey if that was their wish. That move came after an escalation of violence in Syria's northwest that saw dozens of Turkish soldiers killed in Syrian government air raids amid an offensive by forces loyal to President Bashar al-Assad aimed at seizing the war-torn country's last rebel bastion.

The Russia-backed military push has forced nearly one million people towards the shut Turkish border, prompting fears of a major humanitarian catastrophe. Already hosting 3.6 million Syrian refugees, Ankara is determined to prevent any further influx from Syria while also accusing the EU of not fulfilling its promises under a 2016 migration deal.

On Saturday, the Turkish president's office said Erdogan plans to be in Brussels on Monday for a one-day working visit, in a statement that came hours after EU foreign ministers' meeting in Croatia on Friday criticised Turkey.

The ministers said Ankara was using the migrants' desperation "for political purposes".

New migrant camps

Also on Saturday, the Greek migration minister said Greece plans to build two new temporary camps to house hundreds of additional asylum seekers who arrived in recent days.

"We want to build two closed centres in [the northern region of] Serres and the greater Athens area with 1,000 places," Migration Minister Notis Mitarachi told Skai TV.

"We need the backing of local communities. We cannot leave all [these] people on the islands," he said.

Mitarachi said the camps would host asylum seekers who arrived after March 1.

Residents of a Serres town rumoured to host one of the camps staged protests earlier this week and local officials declared their opposition to the plan.

More than 1,700 migrants have landed on Lesbos and four other Aegean islands from Turkey over the past week, adding to the 38,000 already crammed into abysmal and overstretched refugee centres.

The new surge has ramped up already high tensions on an island that has been on the migration front line for years.

Frustration exploded into violence last weekend with mobs setting up roadblocks, attacking cars carrying NGO workers and beating journalists.