MOSCOW, Aug 12 (Reuters) - Russian authorities announced a new criminal charge against Kremlin critic Alexei Navalny on Wednesday (Aug 11), the latest move in a crackdown ahead of September's parliamentary election that could add as much as three years to his prison term.

Navalny, President Vladimir Putin's fiercest domestic critic, is serving a 2.5 year sentence for parole violations he calls trumped up. He was arrested after flying back from Germany where he had recovered from a nerve agent poisoning.

The Investigative Committee, which probes serious crimes, said in a statement that Navalny had been charged with creating an organisation that "infringes on the personality and rights of citizens", a crime punishable by up to three years in jail.

A jail term of that length could keep Navalny in custody past the next presidential election in 2024 when Putin's current six-year term in the Kremlin is due to end.

The Investigative Committee said that Navalny's Anti-Corruption Foundation had incited Russians to break the law and take part in unauthorised protests demanding his release in January that authorities said were illegal.

Navalny and his allies have faced pressure for years, but his political network was outlawed in June after a court formally labelled his anti-corruption foundation and regional campaign groups as extremist.

Several of his closest allies have left the country for fear of prosecution, and his team has also disbanded their regional groups to protect activists.

Allies who post on social media under the name Team Navalny described the accusation as "the latest meaningless charge".

"No one infringes on the personality and rights of citizens like Putin himself and all his henchmen, including the Investigative Committee," they said on Telegram messenger.

The charge comes a day after the Investigative Committee on Tuesday announced a new criminal investigation into two close Navalny allies, who are based abroad, for raising funds for his political network.

On Sunday, Russian media outlets reported that Lyubov Sobol, a close Navalny associate, had left Russia and flown to Turkey. She has not commented on her whereabouts and her allies have declined to comment.