Two men have been arrested after a series of suspicious fires were lit in a pine plantation north of Perth overnight.

The WA Police Air Wing aircraft spotted at least six bushfires at the Gnangara Pine plantation just after midnight, prompting calls to the Department of Fire and Emergency Services (DFES) police and the arson squad.

A vehicle of interest nearby was sighted from the air, and two men – aged 23 and 30 – were taken into custody, and are assisting with inquiries.

Two water bombers and more than a dozen volunteer fire crews were still battling the blazes on Friday morning, dampening problematic areas.