A fire erupted overnight in a private illegal nursing home in the Siberian city of Kemerovo, killing 22 people, Russia's investigative committee said Saturday.

"A fire broke out overnight in a private property used as an illegal nursing home," the investigative committee said on Telegram, adding that "the death toll has risen to 22."

An earlier statement said 20 people had died.

"Six more were injured, two of them were hospitalised and are in a serious condition with burns" the Telegram statement added.

The fire spread over 180 square metres in a two-storey wooden building, the Russian state-run news agency TASS reported.

In a video released by the emergency services, a long row of emergency vehicles lined up outside the burning building, as firefighters tackled flames which sent plumes of smoke into the night sky.

Images released by emergency services showed the building later completely burned out.

"The preliminary cause of the fire was a violation of fire safety rules when operating a heating stove," the Kuzbass regional administration said on its website.

Russia's investigative committee, which investigates major crimes, said it opened an investigation into causing death by negligence.

In 2018, a fire in a shopping mall in Kemerovo killed 60 people, including children and teenagers.