Blackstone has invested £320m (€404m) in a London office property for its new core-plus strategy, as it moves towards larger assets.

The US investor said it had bought 125 Old Broad Street from Brookfield Property Partners, its second deal in London’s City financial district this year, following the £300m acquisition of Alban Gate from The Carlyle Group in April.

Blackstone, known as an opportunistic investor, is using its scale to acquire large, core-plus assets with a view to selling stakes to third-party investors. Last month, the firm sold an 18% stake in Alban Gate to the Virginia Retirement System for €67m.

Ken Caplan, head of European real estate, said Blackstone continued to believe strongly in London.

In the US, Blackstone has bought a 49% stake in One Market Plaza in San Francisco for $600m, as well as making a $968m entity-level investment in the US east coast retail specialist Edens Investment Trust. Interests in the investments have been partially sold to pension funds including the State of Wisconsin Investment Board.

The core plus strategy, which has so far invested more than $2bn globally, is targeting major markets in Europe and the US, starting with the office sector.  As well as London and San Francisco, Blackstone is also targeting Paris, Frankfurt, New York City and Washington DC.

The 125 Old Broad Street deal comes less than a year after Brookfield took full control of the 328,300sqft property.

Brookfield took full ownership of the development in October last year, acquiring the remaining 50% stake from a joint venture between GE Real Estate and Kennedy Wilson. Brookfield acquired its initial 50% share from Hammerson in June 2012.

Built in 2008 and fully-let, the building includes tenants DTZ and Gide Loyrette Nouel.