Spokeswoman: Russia has yet to establish official cause of Navalny's death

Russian investigators have yet to determine the official cause of opposition leader Alexei Navalny's death, his spokeswoman said on Monday, after prison authorities said he suddenly dropped dead following a walk in the "Polar Wolf" penal colony.

The death of Navalny, a former lawyer, robs the disparate Russian opposition of its most charismatic and courageous leader as President Vladimir Putin prepares for an election that will keep him in power until at least 2030.

The West and Navalny's supporters have dismissed the Russian prison service's statement on Friday that the 47-year-old had lost consciousness and died. Western leaders have cast Putin as a killer and said he is responsible for Navalny's death.

Putin has made no public comment, but Russian officials scolded Western leaders for rushing to conclusions about the death, which has further deepened a schism in relations between Moscow and the West caused by the Ukraine war.

Navalny's mother, Lyudmila, was told on Saturday at the prison colony that he had perished from "sudden death syndrome," a vague term for different heart conditions that end in death, according to Navalny's team.

Navalny's spokeswoman, Kira Yarmysh, said his 69-year-old mother and lawyers were informed that the official verification of the cause of death had been extended and that it was unclear how long it would take.

"The cause of death is 'undetermined,'" said Yarmysh, who accused the Russian authorities of lying and stalling.

His mother and lawyers were not allowed into the morgue on Monday in the Arctic town near the prison colony where the authorities said he dropped dead, Yarmysh said.

"Asked if Alexei's body was there, the staff did not answer," said Yarmysh.

Navalny had been incarcerated at the IK-3 penal colony north of the Arctic Circle in Kharp in the Yamalо-Nenets region about 1,900 km (1200 miles) northeast of Moscow.

Just the day before his death, Navalny was shown joking in court via a video link to court. He teased the judge, suggesting he used some of his vast salary to top up Navalny's account.

Reuters