Two Russian intelligence agents have gone on trial in Qatar charged with murdering a former Chechen president.
Yanderbiyev was killed in a February car bombing in Qatar
The two Russians were arrested shortly after the February car bombing that killed Zelimkhan Yanderbiyev and hurt his son Dawoud in the tiny Gulf state.
Prosecutors allege the agents detonated explosives under Yanderbiyev's car as he left a Doha mosque after prayers.
Russia, which sent lawyers to the hearing, denies its agents were involved and demands their release.
The two men, bearded and handcuffed, pleaded not guilty to 10 charges when they appeared in the Doha court, the Associated Press reported.
The charges include murdering Yanderbiyev, attempting to murder his son and destabilising security in Qatar.
Qatar's general prosecutor, Saad al-Dousari, told the court the two men entered the Gulf state illegally from Saudi Arabia with help from the Russian Embassy in Riyadh.
The incident has threatened to harm relations between the two nations.
Russia has accused Qatar of aiding terrorism by allowing Yanderbiyev - president of the breakaway republic from 1996 to 1997 - to live in the country for the past three years.
Last month, Qatar expelled the first secretary of the Russian embassy over alleged involvement in Yanderbiyev's killing.