A court in Russia-annexed Crimea has extended the detention of Crimean Tatar leader Nariman Dzhelyal until January 23, his lawyer Mykola Polozova said.
Dzhelyal was arrested with four colleagues in early September on suspicion of involvement in an attack on a gas pipeline and initially ordered held for two months.
Ukraine has called the charges against Dzhelyal fabricated, while the United States has called for Russia to release him.
Dzhelyal is deputy chairman of the Crimean Tatar's self-governing assembly -- the Mejlis -- which was banned by pro-Moscow representatives in Crimea after the annexation in 2014.
The arrest of Dzhelyal and his colleagues immediately sparked a protest outside the Crimean office of Russia’s Federal Security Service (FSB) that ended with the detention of more than 50 people.
The Russian news agency Interfax in September reported that the criminal investigation against Dzhelyal relates to a gas pipeline that was damaged on August 23 in a village near Crimea’s capital, Simferopol.
Ukrainian Deputy Foreign Minister Emine Dzheppar said at the time that the detention of the five men was Moscow's "revenge" for a Kyiv conference dedicated to the "de-occupation" of Crimea that Dzhelyal had taken part in in August.
The event had been decried by Moscow as “anti-Russian.”
The court earlier this month sent Dzhelyal to a psychiatric hospital for evaluation, a pressure tactic the Kremlin has often used against political opponents.