A notorious gang leader in Russia's North Caucasus, Alexander Tikhomirov or Said Buryatsky, killed in a police sweep on Tuesday, was linked to the derailment of the luxury high-speed Nevsky Express in November 2009, the head of the Federal Security Service said on Saturday.

"DNA tests of the killed militants have been carried out to establish linkage to the derailment of the Nevsky Express in November 2009. These materials give ground to assume that it was they who took part in this attack," Alexander Bortnikov said.

Tikhomirov and five other militants were killed during a special operation on Tuesday in the southern Russian republic of Ingushetia.

Bortnikov said that police found evidence confirming that the militants were linked to the Nevsky Express derailment. They also find bomb-making materials identical to those used in a previous attack on another Nevsky Express luxury train in 2007.

KRASNAYA POLYANA (SOCHI), March 6 (RIA Novosti)