Oy Karelian Trains Ltd is a joint venture agreed on 23 November 2006 between Russian Railways (RZhD) and VR Group (Finnish Railways) to facilitate the operation of international express passenger rail services between Helsinki, Finland, and Saint Petersburg, Russia. Karelian Trains is registered in Helsinki; VR and RZhD both own 50% of the shares. The services are branded as Allegro.
Services were launched on 12 December 2010 using Alstom Pendolino trains ordered in September 2007. Investments will also be made in infrastructure to enable higher speeds to be achieved. Together, this has cut journey times between the two cities from the previous 5½ hours to about 3 hours. There are four daily train departures each direction, compared to two for the older service. The daily night train Helsinki-Moscow will continue like before.
Visas are required for many foreign nationals, including Finns, to enter Russia and for Russians to enter Finland. Passport and customs checks is conducted on board the trains. Traditionally the passport and customs checks has delayed the trains at least 30 minutes according to the time table (1 hour for 30 km Vyborg-the border).
During the first year of operation the service has had 280,000 passengers, far more than expected.
Rolling stock 
The service between Helsinki and St. Petersburg is provided using four Alstom-built Pendolino trains similar in interior fitting and exterior appearance to the VR Class Sm3 Pendolino trains that have been operated by the VR since 1995. The new trains, branded Allegro, are dual voltage, capable of operating on VR's 25 kV AC and RZhD's 3 kV DC electrification systems. The Allegro trains will be painted in a new livery inspired by the colours of the flags of Finland and Russia, with blue and red stripes on a white and silver background, and a blue undercarriage.
See also 
- Finland station, St. Petersburg
- Helsinki Central railway station
- Riihimäki-Saint Petersburg railroad
- "Karelian Trains gets go-ahead". Railway Gazette International. November 2006. Retrieved 5 September 2007.
- "Uudesta Helsinki-Pietari-junasta Allegro". HS.fi (in Finnish). Helsingin Sanomat. 29 December 2008. Retrieved 29 December 2008.
- "Allegro launch cuts Helsinki - St Petersburg journey times". Railway Gazette International. 13 December 2010.
- "Karelian Trains awards Pendolino contract". Railway Gazette International. 5 September 2007. Retrieved 5 September 2007.
- Express train success
- "Allegro: the new high-speed rail connection between Helsinki and St. Petersburg". Press release. VR Group. 29 December 2008. Retrieved 29 December 2008.