MOSCOW (AP) — A Russian court extended probation for opposition leader Alexei Navalny by one year Friday, a sentence that should bar him from running for office until at least 2021.

Navalny, who rose to prominence with his investigations of official corruption, spearheaded a series of anti-corruption protests across Russia this year, the most wide-spread in decades.

He wants to run for president of Russia next year and has been signing up campaign volunteers even though he technically is ineligible as a candidate. He says banning him from office is illegal and he's campaigning to put pressure on authorities.

A lawyer by training, Navalny was convicted of fraud in 2013 and 2014 after trials that supporters characterized as politically motivated.

He was given a 5-year suspended prison sentence along with 1½ years' probation this year after a retrial of one of the cases.

The court in Moscow on Friday granted a motion filed by penitentiary officials who asked for Navalny to be kept on probation a year longer, until December 2020.

The officials argued that he has repeatedly violated the terms of his suspended sentence.

Navalny has signed up more than 130,000 volunteers in more than 60 cities across Russia.