Russian opposition leader Alexei Navalny’s allies have called for a new protest across the country to demand his release from prison.

In a statement posted on Mr Navalny’s website, they urged Russians to sign up for a protest on an interactive map and said they will set a date for it when the number of people willing to take part reaches at least 500,000 nationwide.

The organisers claimed in a YouTube statement that the rally would the biggest Russia has seen. They set up a dedicated website for the protest, inviting those willing to take part to register on the interactive map.

Leonid Volkov, Mr Navalny’s chief of staff who has lived abroad since 2019, said: “When the number of us is big enough, we will choose a convenient date and stage a peaceful march in all Russian cities.”

Another top associate of Mr Navalny, Maria Pevchickh, said: “Our main enemy is indifference, apathy, being apolitical. No one will give us freedom as a gift, it can’t be bought. We must fight for it.”

The 44-year-old Mr Navalny, who is President Vladimir Putin’s most outspoken foe, was arrested on January 17 upon his return from Germany, where he spent five months recovering from a nerve-agent poisoning that he blames on the Kremlin. Russian authorities have rejected the accusation.

Last month, Mr Navalny was sentenced to two-and-a-half years in prison for violating the terms of his probation while convalescing in Germany.

The sentence stems from a 2014 embezzlement conviction that Mr Navalny has rejected as fabricated – and which the European Сourt of Human Rights has ruled to be unlawful.

Mr Navalny’s arrest fuelled a series of protests that drew tens of thousands to the streets across Russia. Authorities have detained about 11,000 people, many of whom were fined or given jail terms ranging from seven to 15 days.

Several top associates of Mr Navalny have faced charges of violating coronavirus restrictions by calling for protests, and have been put under house arrest.

Russian officials have dismissed demands from the United States and the European Union to free Mr Navalny and stop the crackdown on his supporters.

Moscow also has rejected the European Court of Human Rights’ demand to release Mr Navalny, describing it as unlawful and “inadmissible” meddling in Russia’s domestic affairs.

Earlier this month, Mr Navalny posted a note confirming that he arrived at a prison colony in Pokrov in the Vladimir region to serve his sentence. The facility stands out among Russian penitentiaries for its particularly strict regime.