BNP Paribas Investment Partners, the asset management arm of the French banking group, has bought a stake in a UK environmental funds boutique to tap into retail demand for green investing.

BNP Paribas has bought a 29% stake in Impax, which is quoted on London's Alternative Investment Market and has about £1.1bn (€1.5bn) under management in a range of public and private equity funds, all focused on clean energy, water and waste.