MOSCOW – Russian opposition leader Alexei Navalny was released on Friday after spending a month in jail for calling for an unsanctioned protest.

Navalny, along with several opposition activists, has led a protest movement earlier this summer against Russian election authorities’ decision to bar nearly two dozen independent candidates from running for the Moscow city legislature in the Sept. 8 election. One of these rallies was the largest anti-government protest that Moscow had seen in eight years.

Speaking to reporters outside the detention facility in Moscow, Navalny vowed to keep fighting against Russian President Vladimir Putin’s government despite the increasing pressure.

“I have no doubts that despite these acts of intimidation and terrorizing that are happening now, like arrests of innocent people, this wave (of protests) will grow,” he said, adding that the government’s heavy-handed tactics shows that popular support for the Kremlin is waning. “They feel it, and they’re scared of it.”

Authorities have clamped down on the demonstrations, refusing to give permission for them, briefly detaining 1,400 people and arresting dozens of protest leaders, including Navalny.

Some of the independent city council candidates were sentenced to several back-to-back short stints in jail. One of them, Ilya Yashin, was sentenced to another 10-day detention earlier this week, which brings the total number of his consecutive arrests to four.

Kremlin officials have dismissed the protests as insignificant, and Putin has warned the protesters that they must abide by the law or face the consequences.

Fifteen people are now in jail on charges of rioting for the rally in July that was largely peaceful. These charges have been largely seen as the Kremlin’s political vendetta against the dissenters.