Islamist rebels claim they shot down a Russian military helicopter which crashed on Tuesday killing 11 people, including high-ranking officers.
Mi-8 helicopters are widely used by the Russian military
The Mi-8 helicopter came down in Russia's North Ossetia region in the Caucasus.
A little known insurgency group said in a statement on a Chechen rebel website that the Mi-8 was taken down, using a shoulder-fired anti-aircraft missile.
Russian military say the most likely cause of the crash was poor visibility.
The defence ministry in Moscow confirmed that two generals were among the dead but has not released the names of those killed.
One of the commanders in the North Caucasus District was among the dead, officials said.
The insurgency group, calling itself the Ossetia Jamaat, claims it shot down the helicopter after receiving intelligence that it was carrying high-ranking officers.
The ministry has not commented on the statement.
Defence ministry officials, quoted in the Russian media, say the aircraft struck a tree in thick fog during exercises near Vladikavkaz, the provincial capital of North Ossetia.
However Russian media quoted investigators saying they are looking into all possible causes, including hostile action.