A bomb exploded on a railway track in Russia's Dagestan province on Sunday, derailing a freight train days after suicide bombers killed 12 people in the region, Russian news agencies reported. Nobody was hurt.
The pre-dawn blast on a line leading from Moscow to the ex-Soviet republic of Azerbaijan caused eight carriages of a train carrying construction materials to derail, ITAR-Tass and Interfax reported, citing police and emergency officials.
Russia is on edge after suicide attacks in Moscow and Dagestan killed more than 50 people in the past week.
Security was tight as President Dmitry Medvedev and Prime Minister Vladimir Putin attended an overnight ceremony on Russian Orthodox Easter - the most important holiday for the country's dominant religion.
On Wednesday, two suicide bombings in the Dagestani town of Kizlyar killed 12 people including nine police officers, authorties said.
That attack came two days after twin suicide bombings in Moscow's metro killed at least 40 and stoked fears of a major campaign of attacks in Russia's heartland by militant based in the heavily Muslim North Caucasus, which includes Dagestan.
In November, a bombing blamed on North Caucasus militants killed 26 people on a passenger train from Moscow to St. Petersburg.
The Chechen rebel leader seeking an Islamist state across the North Caucasus has claimed responsibility for the Moscow metro bombings. Russian authorities said on Friday that one of the bombers was a 17-year-old Dagestan native, the widow of a militant killed by Russian forces.
Like neighbouring Chechnya and nearby Ingushetia, Dagestan has been plagued by an upsurge of violence in the past two years, with frequent attacks targeting law enforcement.
Sunday's blast left a crater on the railbed and damaged some 44 yards of track, ITAR-Tass cite railroad police as saying.
A passenger train from Siberia to Azerbaijan's capital Baku was stranded on the track by the damage, it said.