The so-called "Courts" in the occupied Crimea ruled to keep in custody all six Muslim activists, detained on the morning of February 17, until mid-April.
Yashar Shikhametov was arrested by the Leninsky District "Court" of Sevastopol city till April 14.
The rest of the Crimean Tatar detainees were arrested by the Kyivsky District "Court" of Simferopol city until April 15.
During the court hearing, Shikhametov stated that FSB officers had planted three books, probably banned, during the search in his house. His Lawyer Oleksiy Ladin intends to file a relevant application to the military investigation committee.
All the Muslim activists are suspected of involvement in the Hizb ut-Tahrir Islamic group, which has been recognised as a terrorist organisation in Russia since 2003 but operates freely in Ukraine and most European countries.
As reported, the Russian Federal Security Service (FSB) operatives raided the homes of seven Crimean Tatars in the early hours of Wednesday, February 17.
The searches were conducted at the homes of Lenur Seydametov (Bakhchisarai), Timur Yalkabov (Akmescit), Azamat Eyupov (Qarasuvbazar), Yashar Shikhametov (Baydar village) ve Abdulboriy Makhamadaminov (Icki district), Ernest Ibragimov (Bakhchisarai) and Oleg Fedorov (Bakhchisarai).
They were taken to the FSB's directorate in Crimea after the searches. Abdulboriy Makhamadaminov was released shortly after.
The six detainees are charged with "setting up of or participation in a terrorist organisation."
Ukrainian Ombudswoman Lyudmyla Denisova said that the detained Crimean Tatars might face long-term arrests.
After the occupation of Crimea by Russia, the invaders started persecuting independent journalists, civil activists, members of the Crimean Tatar national movement, the Mejlis, as well as Crimean Muslims suspected of links with the international Islamic political organisation Hizb-ut Tahrir.
Hizb-ut Tahrir is a global organisation based in London that seeks to unite all Muslim countries into an Islamic caliphate, while rejecting terror tools to achieve their goal. It is banned in Russia as a terrorist organisation but operates legally in Ukraine.
Rights groups and Western governments have denounced what they describe as a campaign of repression by the Russian-imposed authorities in Crimea, who target members of the Turkic-speaking Crimean Tatar community and others who have spoken out against Moscow's takeover of the peninsula.
Russian occupation of Crimea
Russia took control of Crimea from Ukraine in March 2014 after sending in troops, seizing key facilities, and staging a referendum dismissed as illegal by at least 100 countries.
The West did not recognise the occupation in response to which sanctions against Russia were introduced. Crimea remains internationally recognised territory of Ukraine.