The court granted a request of the Prosecutor General's Office to keep Musa Vakhayev, who is accused of killing the 41-year-old journalist on July 9, 2004, in custody for another three months.
The prosecutor said the custody had to be prolonged because parties to the case needed more time to study the 40 volumes of the case.
Belarussian police arrested two native Chechens, Vakhayev and Kazbek Dukuzov, in Minsk (the capital of Belarus) on November 17 last year at the request of Russian security services. They were later handed over to the Russian side.
Earlier, Russian prosecutors said the investigation into the killing of Khlebnikov, who had been with Forbes since 1989, had been completed.
According to the investigation, Vakhayev and Dukuzov arrived at Khlebnikov's office in a Lada car with false number plates, and shot him with a Makarov pistol when he was leaving the building.