A spokesperson from Tumut RFS said the blaze was currently estimated to have a 300 metre front, spreading between 10 and 50 hectares.

"The fire is in very inaccessible country," they said.

"We are positioning crews to protect properties as there are a number in close proximity to the blaze."

In a statement made on Facebook, the Riverina Highlands RFS said aviation and heavy plant are supporting the ground crews, asking residents to avoid the area.

"We have a large air tanker there at the moment to lay a carbon trail onto the fire, and a fix-winged single engine bomber," the Tumut RFS spokesperson said.