Nikolai Shepel, the deputy prosecutor general, said an arms cache discovered on June 22 in Ingushetia (North Caucasus) also contained an archive that is thought to have belonged to Chechen warlord Shamil Basayev.
Shepel said prosecutors had authentic videocassettes showing preparations for terrorist attacks.
"We have tapes showing attacks on government buildings in December 2002 and preparations for the theater siege. The tapes show other facilities in Moscow, such as airports," Shepel said.
Shepel said the cassettes would help investigators uncover the reasons behind and the circumstances of the attack on the theater and other attacks that were planned but not carried out.
Information on the cache came from a member of the gang that seized a school in the North Ossetian town of Beslan, the North Caucasus, in September 2004. The investigation into the Beslan tragedy has uncovered a whole network of illegal extremist organizations in southern Russia that are seeking to force the secession of individual Federation members from the Russian state.
Shepel said investigators were continuing to study the archive. "So far they have only watched the video tapes, because this could be done quicker than anything else," he said.
