NSW Rural Fire Service units from Cobar and Louth were called out to the first fire on the Louth Road about two kilometres from Cobar, with a second fire reported shortly afterwards near the railway line between Cobar and the CSA mine.

Cobar police also attended and an investigation's underway into the cause of the fires.

"Suspicious fire activity has been a relatively rare occurrence in the Cobar area and it is disheartening that this worrying behaviour appears to be on the increase," a spokesperson for RFS Far West team said.

"This summer has already been a busy one for our local firefighters and the last thing they need is deliberately-lit fires that could put both the firefighters and their community at risk."

Residents have been urged to report suspicious behaviour to police immediately.