MOSCOW, April 1 — Jailed Kremlin critic Alexei Navalny lost eight kilogrammes before he went on hunger strike, his team said today, as allies have expressed deep concern about his deteriorating health.

Navalny, President Vladimir Putin’s most vocal critic, went on hunger strike yesterday to demand proper medical treatment for his back pain and numbness in both legs.

In a post on Facebook, his team said that Navalny, who is 189 centimetres (six feet two inches) tall, weighed 93 kilogrammes (205 pounds) when he arrived in his penal colony.

"Right now he weighs 85 (kilogrammes). That is minus eight kilogrammes even before the hunger strike,” the team said.

The allies said Navalny linked the weight loss to sleep deprivation that the 44-year-old called a form of "torture”.

"They are still not allowing a doctor to visit,” the team said, adding Navalny’s diagnosis was still not clear.

The statement said doctors now suggested that he be treated with nicotinic acid.

The opposition politician is serving two-and-a-half years on old fraud charges in a penal colony east of Moscow. He was arrested when he returned to Russia in January from Germany, where he had spent months recovering from a near-fatal poisoning he blames on the Kremlin.

Navalny says he is suffering in prison from severe back pain and numbness in his legs and has only been given painkillers. — AFP