Backburning on the New South Wales mid-north coast overnight has successfully controlled a bushfire that investigators believe was deliberately lit.

Around 1pm AEDT yesterday, firefighters were called to a blaze at Booti Booti National Park, which is located near Forster.

The fire burned into bushland and caused a large amount of smoke to hang over the area.

A number of roads were closed, which isolated the town of Green Point.

By the early hours of this morning officers declared the blaze under control, after a backburn of more than two kilometres.

A short time later police escorted locals back to Green Point.

Investigtions are underway to pinpoint what caused the fire, which is now being treated as suspicious.

The rest of New South Wales has a very high fire risk today, with the Southern Riverina under a total fire ban.