US hotel group Starwood Capital is to sell four key French properties, including the famed Martinez in Cannes and the Concorde Lafayette in Paris, to a Qatari investor, said a senior official.

Starwood Capital's Groupe du Louvre will hold a meeting on Thursday with the sale of the Martinez, Concorde Lafayette, Hotel du Louvre and the Palais de la Mediterranee in Nice on the agenda, union representative Claude Levy said.

Starwood Capital in Paris declined to comment on the sale.

'A promise to sell has been signed recently and there will be an announcement on the matter on Thursday The sale has been imminent for a while,' said Levy.

A source close to the sale said the buyer was Katara Hospitality, formerly known as Qatar National Hotels Company, which is looking to extend its luxury hotel portfolio. Katara Hospitality notably owns Paris's luxury Peninsula hotel that is to open next year.-Reuters