At about 2.15am on Monday, Highlands firies received a call out for a fire at the council's Resource Recovery Centre (RCC) on Berrima Road.

A Fire and Rescue NSW (FRNSW) media spokesperson said fire fighters received a call about a large pile of mulch being alight at the RCC.

The spokesperson said it was a "deep seated fire", which meant the blaze was within rubbish at the site.

They said this made the extinguishing operation more complex for fire fighters.

The cause of the fire remains unknown.

At about 9.40pm Monday, the fire appeared contained, but strong winds caused another flare up.

A front end loader was brought in at 1.30am Tuesday to pull the pile apart for firies to gain better access to the blaze.

The winds continued to strengthen overnight and reached about 90km/h at 3.45am.

Fire fighters continued to monitor the blaze at the time of going to press.

Moss Vale, Bowral, Mittagong and Bundanoon FRNSW crews and Moss Vale Rural Fire Service personnel attended the scene.

FRNSW personnel from outside the region also headed to Moss Vale to assist with the operation.

The RRC was closed for the rest of Monday but re-opened the gates on Tuesday.

A council spokesman said there was no damage to any other facilities or buildings.

The spokesman said the RRC had a "limited opening".

Residents are advised not to bring green waste or concrete resources to the centre.

The Reviva shop within the RRC site will remain closed on Tuesday.

The spokesman recommended residents stay away from the RRC for the next few days.

The NSW Environment Protection Authority has been advised of the incident and will monitor the situation.