Investigators looking at the possible cause of the blaze that killed 10 elderly residents and injured several more at Siberian nursing home believe a discarded cigarette is the most likely cause.

The fire started on the upper floor of the three-storey brick building in the early hours of Thursday morning.

According to the local emergencies ministry, the building had recently been renovated and a newly installed fire alarm woke residents. Staff then began to evacuate the building allowing the majority to escape.

“Fire engines arrived at the scene just minutes after the signal was received. But unfortunately by that time the fire seized the third storey,” Vladimir Gurzhev from local emergency ministry stressed.

Four wards were already on fire and the blaze had spread to the roof.

Due to the age of the residents – many had difficulty walking – rescue efforts were being hampered.

Staff and the emergency services managed to evacuate more than 300 people to safety but 10 elderly people died – all of them men – others with severe burns were taken to a local hospital.

“Our intensive care department got four patients. Three are in serious condition, the other one is more or less alright,” chief doctor of the city hospital, Valentina Malkova, said.

It took two hours to put out the fire and the residents were temporarily housed in two local schools and a children's home.

A spokesman for the Emergencies Ministry said an investigation is now underway into the cause of the blaz- and they would also be looking at whether all employees at the home were actually on duty when the alarm was raised.