Boutique accommodation targeted at 'Millennials' is to open on Cork's South Mall after planning permission was granted to convert the former National Irish Bank premises into a 58-bed hotel.

The building is located at 71 South Mall in the centre of the street at the junction with Morgan Street and has been idle since Danske Bank/NIB closed its 27 Irish branches in 2012.

The five-bay banking hall will be kept for bar/restaurant/cafe use, and the four-storey building will be upgraded, with over 12,000 sq ft added behind in a five/six-storey building for 58 bedrooms, with a roof deck.

There will be guest access to the hotel from the narrow Morgan Street which links Oliver Plunkett Street to South Mall, where the bank branch had a cash transfer depot/access.

The developers will also refurbish the adjacent Morgan St with a cobblestone finish in a similar way to Beasley St which runs alongside the new Maldron Hotel, also on the South Mall.

The developers said the hotel will be operated under the SML brand, a new compact-room accommodation brand being rolled out by the owners. They said the hotel will be primarily aimed at the 'Millenials' market sector of younger travellers.

"Compact or micro hotel rooms, are the fastest-growing hotel sector worldwide," they said, adding that the South Mall hotel will be operated by NHance Management who run a number of hotels throughout Ireland including The Ice House in Mayo and Stauntons on the Green in Dublin.

Planners in City Hall this week granted permission to South Mall Hospitality Ltd for the development.