At least 20 people have been killed after a blaze swept through a home for the elderly in the Siberian city of Kemerovo, Russian officials say.

Another six people were injured. The entire top floor of the two-storey wooden building was gutted by the overnight fire.

Initial reports say it may have been caused by a faulty heating boiler.

The private home for the elderly was operating illegally, officials were quoted as saying by Tass news agency.

Dozens of firefighters were deployed and the blaze was extinguished early on Saturday.

The governor of the region said all similar facilities would now be inspected.

A criminal inquiry has been launched.

Local fire service officials told Tass that many unregistered homes for the elderly were operating across Russia. As such, they were considered private property and not be subject to fire safety inspections.

In 2018, 60 people - including 37 children - died in a leisure centre fire in Kemerovo.