There was no word on who might have planted the bomb on or near train tracks in the Novosibirsk region, some 2,800 km (1,750 miles) east of Moscow.
It exploded with the force of about one kilogram (2.2 pounds) of TNT, the Interfax news agency quoted investigators as saying. Trains on the line were diverted to a parallel track, the report said.
Bomb attacks in Russia are rare outside the North Caucasus region, where Islamist insurgents are waging a campaign they say is aimed at carving out a Muslim state.
The insurgents claimed responsibility for a bombing that killed 26 people on a passenger train travelling between Moscow and St. Petersburg in November 2009. (Reuters)
