Dozens of migrants crossed into Finland on Friday, hours before the reclosure of two southern crossing points on the border with Russia as the Nordic country experiences an influx of asylum-seekers.

The Vaalimaa and Niirala crossings had reopened briefly Thursday after being shut down at the end of last month, along with Finland’s six other posts on the border with Russia.

Finland blames Moscow for sending migrants to the border in an effort to destabilize the country, which joined NATO in April. Russia denies the accusation.

“This is an exceptional phenomenon. We have never seen traffic like this before,” deputy border commander Samuli Murtonen told Finnish broadcaster YLE.

Already by late Thursday, the Finnish Border Guard had reported that dozens of migrants without proper documentation or visas had arrived at the two checkpoints.

However, the Finnish government decided the same day to close them again, effective Friday as of 8 p.m. They will remained sealed until Jan. 14.

The brief reopening was meant as a trial to see whether the migrant “phenomenon” still exists at the border, according to the Finnish government.

At the end of November, Orpo’s government opted to close the entire 1,340-kilometer (830-mile) border for at least two weeks over concerns that Moscow was using migrants to destabilize Finland in an alleged act of “hybrid warfare.”

Finnish authorities say that nearly 1,000 migrants without proper visas or valid documentation had arrived at the border since August until end-November, with more than 900 of them in November alone. The numbers are much higher than usual.

Finland accuses Russia of deliberately ushering migrants — most of whom are seeking asylum in Finland — to the border area, which are normally heavily controlled on the Russian side by the Federal Security Service, or FSB. The Kremlin has denied that Russia is encouraging migrants to enter Finland and has said that it regrets the Finnish border closures.

There are eight crossing points for passenger and vehicle traffic on the Finland-Russia land border, and one rail checkpoint for cargo trains. As of Friday evening, only the rail checkpoint will remain open between the two countries.

Earlier in December, Finnish authorities said that the vast majority of the migrants who arrived in November hailed from three countries: Syria, Somalia and Yemen.

Finland, a nation of 5.6 million people, makes up a significant part of NATO’s northeastern flank and acts as the European Union’s external border in the north.

AP