Russian investigators said they have launched a probe into allegations raised in a documentary film that claimed an opposition protest leader was seeking to overthrow President Vladimir Putin's government with foreign backing. The film, "Anatomy of a Protest II", is a sequel to a documentary aired in March that claimed the opposition had bribed people to attend rallies. The follow-up film -- which, like the original, aired on popular television channel NTV -- focuses on young radical leftist Sergei Udaltsov, leader of the Left Front movement, a key player in the country's anti-Putin protest movement. The film claims Udaltsov is planning to overthrow the government with backing from a Georgian lawmaker and former Bank of Moscow president Andrei Borodin, who is in exile in Britain. It also alleges the Left Front leader is considering hiring Chechen militants to stage an attack. Russia's Investigative Committee said it had launched a probe into the film's claims. "The Investigative Committee is looking into the facts of organisation of mass riots in Russia, as shown in the documentary movie 'Anatomy of a Protest II'," the committee said in a statement late Saturday. The film, which aired Friday, shares the original's jerky camera style and doomsday narration. "The plan of action has already been worked out. Its authors are abroad," the narrator says, as scenes of clashes between protesters and police during an anti-Putin protest rally fill the screen. Udaltsov called the movie the "delirium of a lunatic", and said any illicit finances or other illegal activities on his part would have already been discovered due to close surveillance and multiple searches of his apartment earlier this year. "The movie's strategic goal... is to prepare public opinion for new repressions," he wrote. The investigation was launched after a senior lawmaker with majority party United Russia, Sergei Zheleznyak, asked prosecutors to check into the movie's allegations and make sure opposition leaders do not leave the country. Thirteen people are currently under arrest for alleged mass rioting during an opposition protest on May 6, with four more barred from leaving Moscow. Putin returned to the Kremlin for a third term in May against the backdrop of an unprecedented wave of protests against his rule.