MOSCOW:Police detained more than 250 people at rallies in Siberia and Russia's Far East on Sunday as supporters of Kremlin critic Alexei Navalny took to the streets to protest his jailing, despite biting cold and the threat of arrest.

The rallies, also set to take place in Moscow and other cities later on Sunday, follow large protests last weekend and are part of a campaign to pressure the Kremlin into freeing President Vladimir Putin's most prominent opponent.

The opposition politician was arrested on Jan. 17 after returning to Moscow from Germany where he had been recovering from a nerve agent poisoning in Russia last summer. He accuses Putin of ordering his murder, which the Kremlin denies.

Police have said the protests have not been authorised and will be broken up, as they were last weekend. Over 4,000 people were detained at those rallies, according to OVD-Info, a protest monitoring group.

In the far eastern city of Vladivostok, where a protest began at 0200 GMT, police prevented protesters from accessing the centre, forcing them to relocate to the waterfront and the frozen waters of the Amur Bay.

Video footage showed protesters chanting "Putin is a thief" as they linked hands and marched on the ice in temperatures of around -13 Celsius (8.6 Fahrenheit).

In Tomsk, the Siberian city that Navalny visited before suddenly collapsing on a domestic flight last August, demonstrators gathered in front of a concert hall and chanted "Let him go!" and held up Russian flags.

OVD-Info said police had so far detained 261 people, including 96 in Vladivostok.

Dozens of people in the east Siberian city of Yakutsk turned out in temperatures of -42 C (-44 F).

"This is the first time I've come to a protest. I'm just fed up with the total lawlessness of the authorities," said Ivan, a protester who declined to give his surname.

METRO STATIONS IN MOSCOW

There was a heavy police presence in central Moscow ahead of the rally due to start at 0900 GMT.

Navalny's supporters in Moscow plan to gather near the Kremlin administration and the headquarters of the FSB, the KGB's successor, where during the Soviet breakup protesters in 1991 famously pulled down a statue of the secret police's founder.

Authorities have closed metro stations in central Moscow and have said they will restrict pedestrian movement in the area due to the protest plans.

Navalny, 44, is accused of parole violations which he says are trumped up. A court is due to meet next week to consider handing him a jail term of up to three and a half years.

The West has told Moscow to let Navalny go and his allies have appealed to U.S. President Joe Biden to impose sanctions on 35 people who they say are Putin's close allies.

Seeking to galvanise supporters at home, Navalny put out an online video this month that has been viewed over 100 million times, accusing Putin of being the ultimate owner of a sumptuous Black Sea palace. The Kremlin leader has denied this.

On the eve of the protests, Arkady Rotenberg, a businessman and Putin's former judo sparring partner, said he owns the property.

Many of Navalny's prominent allies were targeted in a crackdown this week. Several, including his brother Oleg, are under house arrest.