MOSCOW (Reuters) - Russian authorities charged opposition blogger and protest leader Alexei Navalny on Tuesday with a financial crime punishable by prison, increasing pressure on one of President Vladimir Putin's leading foes.

The federal Investigative Committee said in a statement Navalny had been charged with organizing large-scale theft following losses suffered by a state forestry firm while he was advising a regional governor, and ordered him to stay in Russia.

It was not immediately clear how long a sentence he could face if convicted.

(Writing by Steve Gutterman, Editing by Timothy Heritage)