A fire has broken out in an unregistered home for the elderly in the Siberian city of Kemerovo, killing at least 20 people, a local news agency quoted emergency services as saying.

The entire second floor of the building had been gutted, fire safety officials told Tass on Saturday, adding that the blaze had later been brought under control.

"At the site of the fire, rescuers continue to work on the rubble in conditions of low air temperature. According to the latest data, 20 people died," the report said.

The officials said many homes for the elderly operated without registration throughout Russia and could not be subject to inspections as they were officially considered private property.

READ MORE:Russia detains suspect linked to deadly bar fire in Kostroma