A fire at a prison in the Chile has killed 81 inmates and injured many more, including a firefighter, according to officials.

The blaze at the San Miguel prison in the Chilean capital Santiago began on Wednesday morning. It is not yet clear what started the fire.

Chilean Minister of Health, Jamie Manalich, called the incident the worst tragedy in the history of the country's jails.

"There has been a terrible tragedy this morning, probably one of the biggest in our prison history. There is a large number of dead and there is also an estimated 14 prisoners seriously injured," he said.

Local radio reported that around 200 inmates had to be evacuated into a jail yard due to the third-floor fire.

Television reports said as many as 19 people were injured.