Alexander Gabyshev began his 8,000-kilometre walk from Yakutia in March.

A Siberian shaman who was detained while on a trek across Russia to banish President Vladimir Putin from the Kremlin has been confined to a psychiatric ward, authorities said Friday.

Self-styled shaman Alexander Gabyshev had walked about a third of the way from his native Yakutia to Moscow, where he planned to expel "demon" Putin, when he was grabbed in the night near Lake Baikal on Thursday.

"Gabyshev was sent today to the Republic's psychiatric clinic" where he would undergo "expert procedures", the Yakutia health ministry said in a statement.

"If pathologies are discovered in this patient, we are ready to offer qualified medical help," it said.

The opposition accused authorities of employing "punitive psychiatry," a Soviet-era tactic widely used against political dissidents, which saw opponents locked up with a diagnosis of schizophrenia or paranoia.

Gabyshev began his 8,000-kilometre (5,000-mile) walk from Yakutia in March, making his way along the country's highway with a simple cart carrying a tent and belongings.

His resilience and direct statements about Putin attracted media attention and sympathy on social networks.

He met supporters as he passed through Russian cities, with some joining his trek and recording his progress on video.

In Ulan Ude last month, his appearance led to clashes after his supporters were detained.

But Thursday, as he and followers were sleeping close to Lake Baikal, Gabyshev was snatched by masked officers who had blocked the highway to carry out the operation, his supporters said.

Police said the shaman would be flown back to Yakutia, where he had allegedly committed a crime.

"Putin really got scared of a shaman with a cart and ordered to lock him up in an asylum. An old KGB method," wrote opposition leader Alexei Navalny on Twitter.

"A person can be held there indefinitely without a court decision or even a case," he said.

After Gabyshev's arrest supporters posted videos of the remaining group continuing the walk, holding flags with the image of the shaman and a slogan "The Shaman's Path: For returning freedom to Russia!"

"Security services arrested our leader... our goal is to continue this walk to secure his freedom," said one of Gabyshev's companions, Viktor Yegorov.