Rockpool evacuated after kitchen fire

More than 100 diners were forced to evacuate renowned Sydney restaurant Rockpool after a fire broke out in the kitchen, causing extensive damage.

The blaze ignited around 8.30pm yesterday, forcing patrons and about 50 staff onto Hunter Street in the city as 20 firefighters arrived on the scene to battle the blaze, NSW Fire and Rescue Superintendent Paul Johnstone said.

"The kitchen has been extensively damaged by fire," he said in a statement.

It is not yet known what started the blaze at the iconic venue, owned by celebrity chef Neil Perry.

No one was injured in the fire.