Another Russian journalist has been detained in Russia for "extremism", accused of making videos for the team of late dissident Alexei Navalny, the Associated Press international news agency said on Sunday.Sergei Karelin, who has worked for the AP, is the second journalist arrested over such allegations after Konstantin Gabov, who occasionally worked for Reuters news agency, was detained on Saturday."The Associated Press is very concerned by the detention of Russian video journalist Sergei Karelin," the agency told AFP.

"We are seeking additional information."Gabov, who according to media reports also worked for Russian television channels Moskva 24 and MIR as well as Belarusian news agency Belsat, will remain in pre-trial detention until at least June 27, the courts' press service said on Telegram.Karelin and Gabov are accused of helping to prepare videos to be published on the YouTube channel NavalnyLIVE, a platform used by Navalny's team, the courts said.Navalny, Russian President Vladimir Putin's most prominent critic, died in murky circumstances in an Arctic prison in February.His movement is designated as "extremist", exposing its staff and supporters to prosecution.Most of Navalny's allies are in exile or serving lengthy prison sentences.The Russian authorities have in recent months stepped up the pressure on independent and foreign media in a concerted effort to silence dissident voices following the offensive against Ukraine.In March, photographer Antonina Kravtsova was also held on "extremism" accusations after frequently covering Navalny's trials for SOTAvision, one of few media organizations documenting political crackdowns in Russia and considered a "foreign agent" by the authorities.Sergei Mingazov, a Russian journalist working for the Russian version of Forbes media, was detained on Friday and accused of spreading "false information" about army abuses in Ukraine.Other jailed journalists include Wall Street Journal reporter Evan Gershkovich, who faces spying claims that he and the US authorities reject.Russian-American journalist Alsu Kurmasheva, who works for Radio Free Europe/Radio Liberty, has been behind bars since October for not registering as a "foreign agent" as required by the authorities.