A Russian rights group says authorities have detained hundreds of people across the country who turned out to mourn the death of jailed Russian opposition leader Alexei Navalny.

The group said more than 400 people have been taken into custody in 32 cities, including Moscow and St. Petersburg from Friday through Saturday.

Navalny, known as a vocal critic of Russian President Vladimir Putin, was reported to have died in prison on Friday.

A spokesperson for Navalny confirmed the information about his death, and said he was "murdered" in a video released on Saturday.
Navalny's mother and lawyer visited the place where prison officials said his body was taken, but found the body was not there.

A senior official of Navalny's support group said they were told that Navalny had died of "sudden death syndrome."

The spokesperson said Navalny's allies will wait for an official announcement regarding the cause of death, and demand his body be handed over to his family.

People continued turning out to pay their respects to Navalny in various locations on Saturday.

In the second largest city of St. Petersburg, mourners gathered at a monument to the victims of repression during the Soviet era. They offered prayers and laid flowers in the presence of security forces.

A 83-year-old woman, who held up a placard reading "Not died, murdered," said her heart aches when she thinks about Navalny and Russia. She thinks the country is heading toward destruction.

She said she no longer believes in the future of her country, and feels Russia is now worse than the Soviet Union under Joseph Stalin's rule.

The woman was later apparently detained temporarily.

Observers say authorities are nervous about the spread of criticism of the Putin administration.