Europe's top human rights and security group said yesterday the death of a Russian opposition journalist in police custody was an "assassination" meant to snuff out dissent in the troubled Ingushetia region.

Police said Magomed Yevloyev, a leading foe of Ingushetia's Kremlin-backed leader Murat Zyazikov, was shot by accident on Sunday when he tried to grab an officer's gun. His supporters and human rights groups dismissed that version of events. The media freedoms monitor of the 56-nation Organisation for Security and Cooperation in Europe (OSCE), to which Russia belongs, condemned the killing as part of "an orchestrated campaign to silence the only critical voice in the region.

"This assassination represents a further deterioration of media freedom in Russia," Miklos Haraszti said in a statement.

"The Russian authorities must promptly and thoroughly investigate Mr Yevloyev's death and all those responsible must be punished," he said from OSCE headquarters in Vienna.

"Russia should live up to its OSCE commitments and support - rather than repress - free debate, free reporting and media pluralism."

Russian media reported that the editor of ingushetiya.ru, Rosa Malsagova, fled Russia this year saying she feared for her life. A Moscow court closed down the site in May, saying it was publishing extremist material.

Mr Yevloyev spearheaded a campaign which tried to prove Ingushetia's authorities had rigged an election last year to give more than 90 per cent support to a pro-Kremlin party.

Mr Zyazikov told Russia's Interfax news agency Yevloyev's killing was a "human tragedy" which would be thoroughly investigated. But he warned he would not allow anyone to use the incident to destabilise Ingushetia.