Finland accuses Russia of trying to destabilise the country by encouraging undocumented migration.
Interior Minister Mari Rantanen said on Thursday that the border crossings in the southeastern regions of Vaalimaa, Nuijamaa, Imatra and Niirala would close on Saturday morning.
The crossings are normally the busiest points of travel between Russia and Finland with about 3,000 people using them per day.
Asylum seekers arriving via Russia will from Saturday have to turn in their applications at two northern border crossings, the government said.
Strained ties
The border closures come amid growing tension between Russia and Finland, which share more than 1,300km (830 miles) of border, over Helsinki’s defence cooperation with the United States.
After Russia’s invasion of Ukraine last year, Finland abandoned its decades-long policy of military non-alignment and joined NATO in April.
Russia said it would take unspecified “countermeasures” in response.
Finland’s Border Guard has since tracked an uptick in undocumented arrivals, mostly from Africa and the Middle East. Finnish officials believe Moscow is encouraging people to go to the Finnish border, where they can apply for asylum.
“It is clear that these people get help to get to the border. This seems like a very conscious decision”, Prime Minister Petteri Orpo said on Tuesday.
Rantanen surmised: “Maybe [Russian officials] are annoyed by something in Finland’s activities.”
The Kremlin, reacting to earlier reports that Finland was mulling a closure, put the blame on Helsinki for deteriorating ties.
“We deeply regret that the Finnish leadership has chosen to deliberately move away from what used to be good relations,” Kremlin spokesperson Dmitry Peskov said on Wednesday.
Finland is constructing a 200km (124-mile) fence on a section of the border, due to be completed by 2026.
At present, Finland’s borders are secured primarily by light wooden fences, mainly designed to stop livestock from wandering into the neighbouring country.