Norway’s sovereign wealth fund has doubled its stake in a central London property for £112.5m (€122m).

Norges Bank Real Estate Management (NBREM) said it had increased its share in 20 Air Street, which is owned in joint venture with UK’s Crown Estate, from 25% to 50%.

The price values the building – which is one of a number of central London assets owned jointly by the two state entities – at £450m.

The NOK7.7trn (€829bn) sovereign wealth fund bought the initial 25% interest from the Crown Estate in December 2013.

The property in Air Street, off Regent Street, has 270,000sqft of office and retail space, and nine residential units.

Norges Bank said the Crown Estate has kept a 50% interest in it and will continue managing the property on behalf of the partnership.

The partnership — called the Regent Street Partnership — was formed in 2010 when Norges Bank made its first property investment, buying a 25% stake in The Crown Estate’s Regent Street portfolio in London.