Emergency services were called to the Commissioners Quay Inn, Blyth, at around 8pm last night.
Five fire appliances attended, three from Northumberland Fire and Rescue Service and two from Tyne and Wear.
A Fire and Rescue Service spokesman said a small fire had broken out on the ground floor of the building, causing minimal damage to the kitchen area. It did not spread to the rest of the hotel.
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It has 40 bedrooms across three floors providing sea views, while a ground floor bar and eating area overlooking the river will provide covers for up to 265 diners inside, with a further 100 covers outside.
The project was developed by Arch, which has been established by Northumberland County Council as an arms-length development company to drive economic development in the county.
It will be operated by the Inn Collection Group (ICG), which has an expanding portfolio of inns, with rooms across the North East.
The development is the second phase of Arch’s investment at Commissioners Quay, adding a further £5million after the opening of Blyth Workspace last year and with a new housing scheme planned later this year.