Russian prosecutors have asked for protest leader Alexei Navalny to be freed pending appeal, hours after he was sentenced to five years in a penal colony for embezzlement.

Navalny was taken into custody immediately after Thursday's sentence in Kirov. His aides said that he would appeal, and had also withdrawn his candidacy for mayor of Moscow in September's election.

However Kirov prosecutors themselves filed an appeal against the verdict, saying Navalny could be freed until the sentence was confirmed by the court of appeal and comes into legal force, a spokeswoman for Russia's prosecutor general told the AFP news agency.

According to the appeal, Navalny, one of Russian president Vladimir Putin's fiercest critics, would only have to sign a pledge not to leave his city of residence.

There was no further explanation about the prosecutor's appeal, but it came after protests in Russia and condemnation from the Europe and the US, who said that it raised questions about the rule of law in Russia and Putin's treatment of opponents.

Protests at sentence

Supporters of the 37-year-old anti-corruption campaigner marched on a local prison following the ruling in Russia's northern Kirov region that found Navalny guilty of stealing $500,000 from a state timber company. Police arrested at least two protesters in a stand-off.

Judge Sergei Blinov said that he had found Navalny guilty of colluding to steal money in a timber deal while acting as an unpaid adviser to the local government.

"The court, having examined the case, has established that Navalny organised a crime and ... the theft of property on a particularly large scale," the judge said.

Navalny, who emerged as a prominent opposition leader last year during anti-Putin protests, had planned to run as a candidate to be Moscow mayor in September against Sergei Sobyanin, a Putin favourite.

If the sentence stood, it could bar also bar him from running in the 2018 presidential election, in which Putin, Russia's dominant leader for 13 years, could try to extend his rule until 2024.

Navalny hugged his wife, Yulia, and his mother, shook his father's hand and then passed them his watch before being led him away in handcuffs.

In a last Twitter message from court, Navalny referred to Putin as a toad who abused Russia's vast oil revenues to stay in power and made clear he expected his supporters to press his campaign.

'Politically motivated'

Navalny messaeged supporters through Twitter [Reuters]

Al Jazeera's Tim Friend, reporting from Moscow, said that Navalny had always claimed that the charges were politically motivated.

"He came to represent the anti-government protests, he is anti-corruption; he is a populist figure and he had considerable support, particularly here in Moscow."

Navalny kept a low profile in the days before the trial verdict, which follows the handing down of a posthumous guilty verdict for whistleblower Sergei Magnitsky by a Russian court earlier this month.

Magnitsky died during pre-trial detention after accusing interior ministry officials of corruption.

The court also found Magnitsky's one-time client, the US-born British investor William Browder, guilty of evading about $17m in taxes this month.

The tax evasion case against Magnitsky was criticised by legal experts and Western governments, including the US, which passed the "Sergei Magnitsky Act" this year.

The act imposed a visa ban and froze the assets of 18 officials implicated in the lawyer's death.

The legislation infuriated Moscow, which in retaliation passed legislation prohibiting Americans from adopting Russian children.