A former deputy prime minister in a Chechen separatist government is accused of ordering the killing of Paul Klebnikov, an American journalist who was gunned down in Moscow in July as he left the offices of the Russian edition of Forbes where he was editor, the Russian prosecutor-general's office said Thursday in a statement.

Prosecutors asserted that Khozh-Akhmed Nukhayev, a Chechen rebel leader, ordered the slaying in response to a book Klebnikov wrote, "Conversations with a Barbarian," in which he had harsh words about Nukhayev and other Chechen insurgents.

Nukhayev's location is unknown, but Russian officials portray him as a onetime mobster who later fought against Russian forces after war broke out in Chechnya in the mid-1990s. He is believed to be active in the Chechen insurgency.

Police arrested two Chechens in September on suspicion of murder in the killing, and prosecutors said Thursday the two were part of a criminal gang that Nukhayev had hired. The prosecutors said two suspects remain at large.

Prosecutors said last week that the two men in custody, Kazbek Dukuzov and Musa Vakhayev, were also involved in the killing of Yan Sergunin, a former official in the government in Chechnya, which is backed by the Kremlin.

In "Conversations with a Barbarian," Klebnikov, who had interviewed Nukhayev at length, argued that the Chechen separatist movement was filled with longtime criminals. Klebnikov was supportive of the Russian military and counter-terrorism campaign in the breakaway republic.

A crusading and controversial journalist, Klebnikov had just overseen the publication of Forbes's list of Russia's 100 richest people when he was killed, initially leading to speculation that someone in the country's business elite might have ordered the slaying. He had also authored a critical biography of Boris Berezovsky, a business leader who was granted asylum in Britain.

Klebnikov, who was of Russian descent, was the first Western journalist to be assassinated in Russia. But at least 21 Russian reporters have been killed here since 2000, according to Reporters Without Borders, which monitors press freedom.