More than 10 per cent of the state's national parks have been burned during the fire season, with a large chunk of the Blue Mountains World Heritage Area impacted.

About 800,000 of the 2 million hectares burnt around the state so far are in national parks. This equates to around 11 per cent of NSW's 7.2 million hectares of national park.

The Ruined Castle fire burns under strong westerly winds in front of Mount Solitary at Echo Point in Katoomba. Credit:Wolter Peeters

The damage has been mostly due to the Gospers Mountain fire which began in November. That alone has ripped through more than 225,000 hectares of land.

As of Tuesday afternoon, this fire was burning in the Wollemi and Yengo national parks, and Parr State Conservation Area, and was being controlled.