Prime Minister Petteri Orpo told a press conference in Helsinki that the last remaining border post, in the Arctic, would be closed until 13 December.
ADVERTISEMENTFinland will close its entire eastern border with Russia due to concerns over migration.
Prime Minister Petteri Orpo made the announcement during a news conference on Tuesday in Helsinki.
Finland had only one remaining border checkpoint open, located in the Arctic after the government closed seven others because of a surge in arrivals of migrants from the Middle East and Africa.
Orpo pointed out that Finland shares a 1,300-kilometre-long border with Russia, which is mostly not fenced.
Finland accuses Moscow of ushering the migrants toward the Finnish border, with the defence minister calling it "hybrid warfare" on the part of the Kremlin.
The last open border station on the eastern border, Raja-Jooseppi in Inari, Northern Lapland, will be closed from Thursday 30 November until 13 December.
“The government has decided to close the entire eastern border," Orpo told reporters, saying the country faced an "exceptional" situation.
“We don’t accept any attempt to undermine our national security," he said.
Finnish authorities say about 900 migrants crossed the border from Russia this month, significantly more than normal. It has accused Russia of trying to create a migration crisis in Finland following the Nordic nation's entry into NATO this year.
Interior Minister Mari Rantanen said the last border crossing for vehicle traffic that remains open, Raja-Jooseppi in Finland's Arctic north, would close at midnight Wednesday.
A railway crossing between the two countries remains open but for cargo traffic only.
According to the Finnish government, Russian authorities have organised and encouraged the migrant flow towards the border, where they are processed in Finland and treated as asylum seekers.
Most of them are young men, from Syria, Yemen and Iraq, and Russia has allowed them to approach the border despite having no travel documents.
Finnish officials believe the move is in retaliation for Finland joining NATO this year.