KASTANIES, Greece (Reuters) - Teargas and smoke bombs clouded a border crossing between Greece and Turkey on Saturday as tensions persisted over thousands of migrants massed at the frontier trying to force their way into the European Union.

A Reuters reporter near the crossing at Kastanies said the projectiles were being fired from Turkey toward Greek police. Some teargas was also fired by Greek police during intermittent exchanges during the day.

In early evening, Greek police deployed water cannons to douse fires lit along the border fence.

Thousands of migrants have been trying to get into EU member Greece since Turkey said on Feb. 28 it would no longer try to keep them on its territory as agreed in 2016 with Brussels in return for billions of euros in aid.

Turkey argued it could no longer contain the hundreds of thousands of migrants it hosts, especially with the likelihood of more refugees fleeing intense fighting in northwestern Syria, but Greece is trying to keep the migrants out.

Greek soldiers and riot police have been manning the borderland as thousands of migrants have made a rush for the frontier in recent days. Their Turkish counterparts have been stationed on the other side.

Greek officials say authorities have thwarted thousands of attempts by migrants to cross in the past eight days. Between Feb. 29 and early Saturday evening, Greek authorities registered more than 39,500 attempts to cross and made 280 arrests, a government source said.

“Greece is doing what every sovereign state has the right to do, to protect its border from any illegal crossings,” Greek Prime Minister Kyriakos Mitsotakis told the CNN network on Friday night.

“I’m afraid this is a constant and very systematic provocation on Turkey’s behalf which has nothing to do with the plight of these people. They are being used by Turkey.”

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Turkey on Friday accused the European Union of using migrants as political tools and allowing international law to be “trampled” after EU foreign ministers said they would work to stop illegal migration into the bloc.

Hundreds of thousands of asylum seekers fleeing conflict in 2015 and 2016 reached the European Union going through Turkey and Greece until an agreement between Brussels and Ankara stopped the flow in March 2016.

However, Turkey still hosts hundreds of thousands of people, and thousands are stuck in limbo in Greece as asylum application reviews crawl forward at a snail’s pace.

Greek police also said on Saturday they had arrested 12 people trying to leave for Austria on forged passports. The detainees, who said they were Syrians, arrived at Athens airport dressed in identical sports kits and said they were members of a handball team heading for a game in Vienna.