Turkey has deployed 1,000 police officers to its border to prevent Greece pushing migrants and refugees back, its interior minister said, as thousands massed at the Greek frontier.

"A thousand special force police officers are deployed from this morning to the Meric River on the border, fully equipped, to prevent people being pushed back," Suleyman Soylu told reporters during a visit to the northwestern province of Edirne on Thursday.

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The river is known as Evros in Greece.

Soylu accused Greece of "mistreating" migrants and refugees and said Turkey "would not allow it".

Turkish President Recep Tayyip Erdogan said last week that migrants and refugees would no longer be stopped from trying to reach Europe, reneging on a commitment to hold them on Turkish territory under a 2016 deal with the European Union.

"Desperation and despair are growing as refugees and migrants take advantage of Turkey's open border with Greece and Bulgaria," said Al Jazeera's Natasha Ghoneim, reporting from the Turkish side of the border.

"Some are taking dangerous risks for the chance to reach the European Union."

Turkey is home to about four million refugees, the majority of them Syrian, and Ankara fears another influx as Russian-backed regime forces push to retake the last opposition stronghold of Idlib.

After Erdogan's announcement, thousands of refugees rushed to the border in Edirne, where there have been clashes with Greek police in recent days.

There have also been arrivals from Turkey to Greek islands such as Lesbos.

Turkey has claimed Greece is using live rounds against migrants, saying at least three people have been killed.

.@NikosDendias do you think it is acceptable to throw tear gas bombs at innocent refugees? Is it acceptable to shoot and kill them? Instead of spreading fake news about us #Greece should treat refugees as human beings, just like #Turkey.#GreeceAttacksRefugees https://t.co/YtR522ZlD4 — Mevlüt Çavuşoğlu (@MevlutCavusoglu) March 5, 2020

Athens has dismissed the allegations as "fake news", saying Turkish forces were helping people to cross the border. Both sides used tear gas at the Kastanies border post on Wednesday.

Investigative website Bellingcat on Thursday said Greek riot police could be using potentially lethal tear gas after expended gas canisters with pointed tips had been found in the vicinity of protests by asylum-seekers at the Greece-Turkey border.

The Greek government said border guards had prevented nearly 7,000 attempted entries over the past 24 hours, and nearly 35,000 over the past five days.

Athens is preparing to deport hundreds of others who made it through.

Deportations

Soylu, who said on Wednesday that Turkey was preparing a case at the European Court of Human Rights over Greece's treatment of migrants, accused Greek forces of wounding 164 people and pushing back nearly 5,000 into Turkey.

The situation at the Kastanies border crossing was calm on Thursday. Migrants - many of whom are from Afghanistan and Pakistan as well as Syria and other Arab nations - huddled in tents and makeshift camps on the Turkish side of the border.

Migrants who arrived in Greece illegally after March 1 will be transferred to the northern city of Serres and deported back to their own countries, Greek Migration Minister Notis Mitarachi said late on Wednesday.

"Our aim is to return them to their countries," he told the Athens News Agency.

Mitarachi also said migrants who entered Greece before January 1, 2019, and are living on its Aegean islands would be transferred to the mainland in the coming days.

Athens announced on March 1 that it would not accept any new asylum applications for a month following the build-up of migrants at the border. This has triggered criticism from human rights agencies.

The Aegean Sea remained choppy on Thursday and there were no further sightings of dinghies carrying migrants to Lesbos and other Greek islands from the nearby Turkish coast.

Lesbos already hosts more than 20,000 asylum seekers, many of them living in filthy conditions in overcrowded camps

Greece and the EU accuse Turkey of deliberately goading the migrants and refugees to cross the border as a way of pressuring Brussels into offering more money or supporting Ankara's geopolitical aims in the Syrian conflict.

Erdogan discussed the migrant issue with senior EU officials in Ankara on Wednesday but his spokesman said the Europeans had made "no concrete proposition" on how to resolve the crisis.

Ankara's change in policy towards the migrants on its soil came after at least 33 Turkish soldiers were killed by Russian-backed Syrian government forces in an air raid in Syria.