Navalny was arrested on Saturday after organising and attending a massive anti-Putin protest in Moscow.

Russian opposition leader Alexei Navalny has been released from detention after he was arrested on Saturday amid widespread protests against President Vladimir Putin.

Navalny was detained in Moscow where he was attending a demonstration organised by him against the inauguration of the Russian president.

Navalny, who has been jailed in the past for organising unauthorised rallies, had called for people critical of Putin’s leadership to take to the streets in advance of the president’s inauguration for a fourth term on Monday.

According to OVD-info, a human rights monitor, about 1,600 people had been detained nationwide during Saturday’s protests.

More than 700 of those arrests made were in Moscow.

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Al Jazeera’s Rory Challands, reporting from Moscow, said it was difficult to tell exactly how many people had shown up at the protests due to different estimations from police and protesters themselves.

“But certainly this is a countrywide event that has brought thousands and thousands of Russians out on to the streets,” Challands said.

The demonstrations are intended to “keep the [opposition] momentum going”, Challands added, following Putin’s recent re-election to office in a ballot Navalny was prevented from entering.

Navalny has been one of Putin’s most staunch opponents. In the run-up to the 2018 presidential elections, Navalny ran a campaign focusing on battling corruption.

However, Navalny was barred from running in the elections after a Russian court reinstated a past criminal conviction for embezzlement.

The conviction had been previously overturned by the European Court of Human Rights, which ruled that Russia did not give Navalny a fair trial.

The European Union said the circumstances surrounding Navalny’s removal from the race cast “serious doubt” on the election.

Putin won the contest with 76 percent of the vote, his best ever showing.

Following those results, Navalny has remained critical of Putin.