Sergei Khadzhikurbanov and brothers Dzhabrail and Ibragim Makhmudov were acquitted in February of involvement in Ms Politkovskaya's death.

But critics said the trial was farcical and Russia's Supreme Court ordered a retrial over procedural violations.

Ms Politkovskaya was a staunch critic of the Kremlin - her supporters allege official involvement in her death.

The Kremlin has dismissed such claims.