A Russian court has handed week-long sentences to several supporters of jailed Kremlin critic Alexei Navalny after they travelled to his penal colony to demand he receive proper medical treatment.

Police on Tuesday detained nine Navalny supporters outside his prison in the town of Pokrov around 100 kilometres (60 miles) east of Moscow for violating public order.

The supporters had gathered outside the colony to demand access to Navalny, who is on hunger strike and demanding medical treatment for back pain and numbness in his legs and hands.

On Wednesday, lawyers from the Agora rights group representing them said four of the supporters had received stints in detention centres ranging from eight to nine days.

Russian police officers guard the entrance to the penal colony where Kremlin critic Alexei Navalny is being held
Russian police officers guard the entrance to the penal colony where Kremlin critic Alexei Navalny is being held AFP / Kirill KUDRYAVTSEV

Three are members of the Alliance of Doctors medical trade union, which is critical of the government and headed by Navalny's personal doctor Anastasia Vasilyeva.

On Thursday, the Agora lawyers said a fourth supporter had received a 10-day sentence.

Navalny went on hunger strike last Wednesday to demand proper medical treatment for severe back pain and numbness in both legs, saying he had only been given painkillers.

He has since said he has also come down with a heavy cough and fever.

On Wednesday, his lawyer Olga Mikhailova said she and another member of Navalny's defence team had visited the opposition figure, who has been moved to the prison infirmary.

Navalny is on hunger strike and demanding medical treatment for several ailments
Navalny is on hunger strike and demanding medical treatment for several ailments Navalny team Youtube page / Handout

She said he is losing sensation in his hands and that an MRT scan had shown that he has two herniated discs in his back, as well as a bulging disc.

Also on Wednesday, several of Navalny's allies, including key aide Lyubov Sobol and his brother Oleg, saw their house arrests relaxed.

The activists have been under house arrest since late January charged with violating anti-Covid measures by attending a Moscow protest in support of Navalny.

A Moscow court said they now face a daily curfew from 8:00 pm until 6:00 am, are barred from communicating with each other and cannot use the internet or phones except in the event of an emergency.

Navalny, 44, was arrested in January after returning from Germany where he was recovering from a nerve agent poisoning he blames on the Kremlin.

He was sentenced the following month to two-and-a-half years in a penal colony for breaching the parole terms of an earlier fraud sentence.

Washington and Brussels have called for Navalny's immediate release and imposed sanctions on Moscow over the poisoning.

White House Press Secretary Jen Psaki said Wednesday that President Joe Biden's administration was "disturbed by reports" of Navalny's worsening health.

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