SIDNEY — The Maine Forest Service is investigating the cause of a fire which burned about a half-acre of field Monday, after a permitted burn over the weekend apparently restarted and spread.

Around 3 p.m. Monday Sidney firefighters called to investigate the source of smoke around 100 or 102 Bartlett Road discovered a field on fire, according to Sidney Capt. Ben Jandreau.

Jandreau said firefighters from Oakland responded to a request for manpower to assist Sidney firefighters at the fire scene, and the fire was extinguished in about an hour.

The Maine Forest Service is investigating, to determine how the fire started.

Jandreau said it appeared a permitted burn, of brush and logs, from over the weekend was never fully put out, and rekindled and spread across the field Monday.

The name of the owner of the property where the fire was located was not immediately available Monday evening.

Jandreau said nobody was at the fire when firefighters arrived.