British Land, the property company, is in talks to sell a landmark Foster & Partners-designed City of London office tower to the Kuwait Investment Authority (KIA) for as much as £400m.

The developer, whose full- year results on Wednesday are expected to show significant falls in net asset value because of the downturn in the property market, is in late-stage talks to sell the headquarters of insurance broker Willis, opposite Lloyd's of London, to the sovereign wealth fund.