MOSCOW • The Berlin hospital treating leading Russian opposition figure Alexei Navalny said yesterday that test results indicated poisoning, contradicting the finding of Russian doctors.

The 44-year-old Kremlin critic and anti-corruption campaigner was taken to the German capital last Saturday after falling ill in Siberia last week with what Russian doctors blamed on a metabolic disorder.

"Clinical findings indicate poisoning with a substance from the group of cholinesterase inhibitors," the renowned Charite hospital in Berlin said on Twitter.

Cholinesterase is an enzyme that is needed for the central nervous system to function properly.

Common side effects of cholinesterase inhibitors include vomiting, muscle cramps, headache and hallucinations.

"Alexei Navalny's prognosis remains unclear; the possibility of long-term effects, particularly those affecting the nervous system, cannot be excluded," the hospital said.

Russia's most prominent opposition figure was rushed into intensive care in Siberia last Thursday after his plane made an emergency landing in the city of Omsk.

Aides say they believe Mr Navalny was poisoned with a cup of tea, pointing the blame at President Vladimir Putin.

Doctors who treated Mr Navalny gave a press conference in Omsk yesterday morning, denying they were influenced by officials while treating him.

"There was no influence on the treatment of the patient a priori and there couldn't have been any," said Dr Alexander Murakhovsky, the chief doctor of the Omsk emergency hospital No. 1. "There was no pressure on us from any doctors or any other forces."

Journalists and Mr Navalny's allies said the hospital was packed with police, and plain-clothes officers sat in Dr Murakhovsky's office.

Mr Navalny has been a thorn in the Kremlin's side for more than a decade, exposing what he says is high-level graft and mobilising crowds of young protesters.

He has been repeatedly detained for organising public meetings and rallies and sued over his investigations into corruption.

He was barred from running in a presidential election in 2018.

AGENCE FRANCE-PRESSE, REUTERS