Thousands of Russians are leaving their country for fear of the authorities declaring a state of war – a measure that will close borders and stifle internal divisions.
The Allegro train between Helsinki and St. Petersburg will be full in the coming days.
VR said it plans to increase the Allegro service to meet demand.
"We’ll try to add a few trips in a couple of days next week," VR: t Lauri Sipponen told Yle.
VR said it was not aware of any security threats to the Allegro link.
"Trains run in the opposite direction [to Russia] are practically empty. From a commercial point of view, this is not a good situation for VR, but we are fulfilling our service obligations," Sipponen said.
Tickets are only available to Finnish and Russian citizens.
Buses from St. Petersburg to Helsinki, Tallinn and Riga are also full.
In the meantime, a steady flow of cars has passed through the border crossing point in south-eastern Vaalimaa.
Russians departing by plane are in serious flight shortages as Western airlines have shut down Russian airlines from their airspace. Russian airlines are now flying to Turkey in a row.
Although the Russian invasion of Ukraine has caused emigration, some Russian citizens are having difficulty returning home.
The Russian Tourism Association has reported that about 27,000 Russian tourists are stuck around the world.
In the coming weeks, several Russian tourists are expected to return home via Finland.
This week’s Yle News All Points North podcast discussed how Russia’s attack on Ukraine will affect Finland.