A man accused of deliberately lighting a deadly blaze that ripped through a Sydney nursing home in 2011 killing 11 elderly residents pleaded guilty Monday to murdering them.

Roger Dean, 37, was a nurse at the facility and entered 11 guilty pleas to murder on the first day of his trial in the Supreme Court.

He also admitted eight counts of causing grievous bodily harm to other mostly infirm residents of the home, some of whom suffered from dementia or were blind.

Three residents perished during the inferno Dean started and eight others died later from their injuries.

Reports said family members of the victims in the packed court room wiped away tears and one woman left sobbing. Others were seen weeping outside.

At the time, Dean, a shift worker, was described by locals as a friendly but quiet man who kept to himself.

The fire led to the New South Wales state government ordering a review of criminal screening of staff at nursing homes and an audit of buildings at all aged care facilities.

Although the home had fire doors and fire extinguishers, it did not have a sprinkler system.

Dean will be sentenced at a later date.