By Chris Dorrell Private equity giant 3i Group upped its dividend as its full year results were boosted by the “remarkable growth story” of Dutch retailer Action. 3i reported that its net asset value (NAV) per share was 2,085p at 31 March, up from 1,745p a year ago. Its total portfolio value was £21.6bn, having surpassed £20bn last November thanks to the rapid growth of Action. 3i owns a majority stake in the Dutch discount retailer, which made up 65 per cent of assets at the end of March. Action generated a gross investment return of 33 per cent after delivering a 28 per cent increase in prof…