Finland will extend the closure of its border with Russia by four weeks, until February 11.
The interior ministry announced the extension on Thursday. The border was set to reopen on January 15.
Finland’s 1,340km (832-mile) border with Russia serves as the European Union’s external border and is part of NATO’s northeastern flank.
It shuttered all eight frontier posts with Russia late last year after accusing Moscow of encouraging asylum seekers and undocumented migrants to cross over. Russia has denied the claims.
“Based on the information gathered by the authorities, the threat of the phenomenon restarting and expanding as previously experienced is likely,” the interior ministry said in a statement.
Finland joined NATO in April after decades of military non-alignment and pragmatic friendly ties with Moscow. It says that Russia has been allowing the movement of migrants in an attempt to destabilise the country and also in retaliation for its decision to increase defence cooperation with the United States.
Last month, when two crossings were opened for a short period, more than 300 asylum seekers entered from Russia within two days, the Finnish Border Guard said at the time.
According to the Border Guard, earlier in November, an estimated 900 asylum seekers from countries as wide-ranging as Kenya, Morocco, Pakistan, Somalia, Syria and Yemen entered Finland from Russia.
Finland is constructing a 200km (124-mile) fence on a section of the border, due to be completed by 2026.