Spa hotels and resorts currently operating under Carlson and Rezidor Hotel Group brands will keep their individual identities after the two groups combined to launch the Carlson Rezidor Hotel Group (CRHG).

Although the brands will be "aligned globally", a spokesperson said properties will continue to be developed under brands such as Missoni, which saw its first spa open in Edinburgh, UK, in 2010.

CRHG has a portfolio of more than 1,300 properties across 80 countries and the legal status and the ownership structure of both companies will remain the same, although it will pursue the global alignment and management of its brands.

Commercial activities will be undertaken under the CRHG name and the new group is also responsible for international purchase opportunities and people development.

It is hoped the group will generate more than US$400m (EUR310m, £259m) in additional revenues, as well as RevPAR Index growth of more than 9 points over the next three years.

A steering committee will oversee the group's development, co-chaired by Carlson president and chief executive officer Hubert Joly and his Rezidor counterpart, Kurt Ritter.

Joly said: "Carlson and Rezidor have a long, common history and have grown together over the past 17 years.

"Going to market as one is a next and natural step. We are leveraging the strengths of two great companies to create value for all our stakeholders."

A new website - www.carlsonrezidor.com - will launch on 1 February.