
Interfax quoted a spokesman for the rescue teams in reporting the higher death toll from the derailment of the high-speed "Neva Express" travelling between Moscow and St. Petersubrg late Friday evening.
Some 100 of the 650 passengers on the train were injured when four of the train's 14 carriages were derailed in what by initial indications was possibly a bomb attack.
Investigators said passengers reported hearing a loud explosion just before the derailment. Later, a 1-metre-wide crater was located beneath the tracks.
While authorities were treating it as a possible terror attack, a police spokesman expressed doubts about a message posted on the internet by a radical right-wing group claiming responsibility.
The Interior Ministry said there were foreigners on the train, and at least one Italian national was being treated in hospital.
Russian President Dmitry Medvedev called an emergency staff meeting of the country's security agencies in the Kremlin on Saturday to deal with the incident.
It was the second such incident on the same train route after an attack in August 2007 which left 60 persons injured. That attack was blamed on Chechen rebels, although it was never fully clarified.
The line is a key transport link in Russia, and is often fully- booked.
The head of the Russian Railways (RZD), Vladimir Yakunin, travelled to the scene of the disaster late Friday night, and announced that the line would be shut indefinitely.
A mobile hospital was flown to the emergency scene, with extra hospital workers, doctors, rescue workers and police reporting for duty.