Moscow (AFP) - Russian opposition leader Alexei Navalny announced he had filed a lawsuit against President Vladimir Putin on Thursday over alleged graft, accusing him of ordering huge loans to a firm owned by his son-in-law. "I sued Putin over Putin's son-in-law and I am sure that I will win," Navalny wrote on his blog, accusing the Russian leader of violating anti-corruption legislation to benefit Kirill Shamalov, who recently married the Russian leader's daughter Katerina.