Russia's security services said on Friday they had found traces of explosives among the wreckage of one of two Russian planes which crashed within moments of each other, calling it a terrorist attack.
The FSB declined to comment on a claim by an Islamist group on the Internet that its followers had hijacked both planes and brought them down, killing at least 89, to avenge the killing of Muslims in Russia's rebel Chechnya province.
"During the examination of the wreckage of the Tu-154 plane traces of explosives were found," an FSB spokeswoman said. "The investigation process produced information which has allowed us to identify a number of people with possible links to the terrorist act that was committed on Tu-154."
She said the explosive was of a type used in some previous attacks blamed on Chechen separatists, including the 1999 apartment bombings which killed about 300 people.
It was a substance called hexogen, more widely known as RDX -- a powder which when mixed with TNT is used as an explosive element in artillery shells and torpedoes.
She said she there was no fresh information about the other plane, a Tu-134.
The Islamist group, calling itself the Islambouli Brigade, said five mujahideen had hijacked both planes, according to an Internet web site. The Arabic-language statement, whose authenticity could not be verified, threatened more attacks.
"Russia's slaughtering of Muslims is still continuing and will not stop except with a bloody war. Our mujahideen were able with God's help to deal a first strike which will be followed by other operations in a campaign aimed at helping our Muslim brothers in Chechnya and other Muslim countries enduring Russia's atheism," the statement said.
