* Pavlensky has history of extreme political protest
* Once nailed private parts to Red Square
* Latest action protest against security service tactics
By Andrew Osborn
MOSCOW, Nov 9 (Reuters) - One of Russia's most radical political performance artists was detained in Moscow early on Monday after briefly setting fire to the entrance of the headquarters of the FSB security service, the successor to the Soviet KGB.
Video footage showed Pyotr Pavlensky standing on Moscow's storied Lubyanka Square in front of the building where political prisoners were interrogated in the Soviet era as flames licked around its entrance, scorching parts of two heavy wooden doors.
Pavlensky, 31, was shown holding a petrol can and staring out onto the darkened square before a policeman grabbed him. His lawyer later told the Interfax news agency that Pavlensky was being held in a Moscow police station and might be charged with arson.
Unnamed law enforcement sources confirmed Pavlensky's detention, saying he could be charged with petty hooliganism, an offence that usually carries a fine and a jail term of up to 15 days. Two journalists filming his actions said they were briefly detained before being released.
In a script accompanying the video of the incident, which was released from one of his own social media accounts despite his detention, Pavlensky said his action was called "Threat" and meant to draw attention to what he called the terror tactics employed by the security agency.
"Fear turns free people into a sticky mass of uncoordinated bodies," he said. "The threat of inevitable reprisal hangs over everyone who can be tracked with devices, have their conversations listened to, and who faces borders with passport control," he wrote.
Pavlensky has attracted attention before, carrying out extreme acts which he says are designed to poke holes in the Kremlin's propaganda machine and draw attention to society's problems.
In 2012, he sewed his lips together to protest against the jailing of anti-Kremlin punk band Pussy Riot, and the following year he wrapped himself in barbed wire in front of a government building to show his opposition to laws he deemed regressive.
In his most shocking act, in November 2013, he nailed his scrotum to Moscow's Red Square, a gesture he described as a metaphor for the political apathy of Russian society.
He was briefly detained in October 2014 after slicing off his earlobe while sitting naked on the roof of an infamous state psychiatry clinic to protest against what he said was the political abuse of psychiatry.
Doctors have declared Pavlensky, who has in the past been ordered to undergo psychiatric tests, as sane.
Public reaction to his latest act was mixed with some Russians taking to social media to laud his bravery and others strongly condemning him. (Editing by Andrew Heavens)
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