PARIS (AFP) - Dozens of firefighters battled a major blaze on Wednesday at the 17th-century Lambert Hotel in central Paris, a private mansion that was bought by a Qatari prince in 2007, the fire service said.

Some 140 firefighters needed around six hours to bring the blaze under control after they rushed to the scene at 1:30am (2330 GMT on Tuesday).

The mansion is considered one of the finest examples of mid-17th-century French architecture, featuring frescoes by Charles Le Brun and other masters of the day, and is part of a World Heritage site along the banks of the river Seine.

The fire, which broke out overnight on the roof of the building, "spread pretty fast because the building is empty and in the midst of renovation", fire service Lieutenant-Colonel Pascal Le Testu said. "The operation was complicated because the structure is fragile," he said.

"Now we have to see how badly the structures were affected as well as the state of the artworks inside that may have been reached by smoke and flames, but also water, despite our utmost efforts to protect them," he added.

Around a dozen neighbours were evacuated, while one firefighter was slightly injured.

Built in the 1640s at the eastern tip of the Ile Saint-Louis, the mansion was designed for a wealthy financier, Nicolas Lambert, by the architect Louis Vau, who went on to oversee an expansion of the Chateau de Versailles for Louis XIV.

Rich with history, the mansion's uses over the years have included being a hideaway for the 18th-century philosopher Voltaire and his lover, and a political headquarters for Polish exiles in the following century.