"An active investigative and operational effort is underway to identify and find the individuals involved in the crime," Vladimir Markin, a spokesman for the investigators, told Russian state television on Sunday, November 29.

The 14-carriage passenger train carrying nearly 700 people was jolted off the rails on the main line between Moscow and Russia's second largest city, St. Petersburg in what the authorities suspect was a bomb attack. According to Russia's emergency situations ministry, the attack killed 25 and injured 104, while 26 people remain missing.

Markin said forensic experts had returned Sunday morning to the scene of the explosion - a wooded area about 400 kilometers (250 miles) northwest of the capital Moscow - to continue their search for clues.

The question of responsibility

It remains unclear what motivated the attackers to strike the train, which is popular with well-off Russians and foreign tourists. A police spokesman expressed doubts about a message posted on the internet by a radical right-wing group claiming responsibility.

The chief of Russia's FSB security service had said earlier that the blast which derailed the train was caused by an improvised explosive device with the force of seven kilograms (15 lbs.) of TNT.

Interior Minister Rashid Nurgaliyev had said police had evidence suggesting that several persons took part in the attack, and even gave a description of one of the suspects.

A second explosion occurred during rescue operations on Saturday, but no one was injured.

Grim task of identifying bodies

Meanwhile, the process of formally identifying bodies began on Sunday in Tver, a city between Moscow and St. Petersburg, and the regional capital of the area in which the train was attacked.

Interfax news agency quoted a spokeswoman for the regional government as saying that 65 relatives of the train disaster victims were in Tver to examine the corpses at a local morgue.

A government commission specially formed by Prime Minister Vladimir Putin to deal with the aftermath of the disaster was expected to meet later on Sunday.

Russian Railways, the state company that oversees the country's railroads, said in a statement that the movement of trains between Moscow and St. Petersburg had been "fully restored" as of Sunday morning.

Past attacks against civilian targets

The Nevsky Express was hit by a similar bomb attack in August 2007, when 60 people were injured in an incident that continues to remain cloaked in mystery although it has been inconclusively linked to Chechen separatists and Russian ultranationalists.

Forty-six people were killed and 160 injured as an explosion tore through a morning commuter train in Russia's southern fringe in December 2003 and, just months later, in February 2004, a suicide bombing claimed 39 lives on an underground train in Moscow.

Extremists from conflict regions in the northern Caucasus have been blamed for a string of attacks on other civilian targets in Russia, including planes and a bus.

rb/AFPE/dpa/Reuters

Editor: Toma Tasovac