A Maitland business has gone up in flames early this morning, but firefighters have managed to contain the damage to one building.

NSW Fire and Rescue duty commander for lower Hunter inspector Jim Murphie told the Maitland Mercury the first crews on scene found quite an advanced fire internally to the Mitchell Integrated Therapy building on High Street, just before 4.30am on February 1.

"We think it originated from somewhere around the car park area or the laundry and the fire may have been burning for sometime before the call came in," he said.

Firefighters were forced to cut their way into the property to contain and extinguish the fire which took approximately two hours.

Inspector Murphie said there is yet to be a determined cause for the major blaze, however Fire and Rescue NSW (FRNSW) investigators from Sydney were on-site to further investigate the cause of the blaze.

FRNSW expert investigators will sift through the debris, using an Ignitable Liquid Detection dog, to determine the cause of the fire.

"At this stage the cause of the blaze is nothing suspicious and there was no sign of forced entry when we arrived," he said.

The crews on scene were able to successfully save the neighbouring building Jaycar which inspector Murphie said the blaze was starting to head towards.

The building and its contents, including four cars, have suffered significant damage.

"Unfortunately most of the interior of Mitchell Integrated Therapy will have to be rebuilt," he said.

"No one has been injured, no persons were inside the premises and no firefighters have been injured."

Fire and Rescue NSW superintendent Garry Tye said the blaze was a small part of the damage to the building.

"The rest of the building has been affected by smoke, heat and water damage," he said.

Three fire trucks were initially sent to the scene after a woman driving by saw smoke coming from the premises - another six and additional support were soon dispatched after first responders saw what they were facing, with about 30 firefighters attending in total.