A new addition to the UK chain of easyHotels has been allowed to open in Belfast despite an issue with room sizes.
It began trading at the weekend following permission from Tourism NI.
However, it has been certified as guest accommodation to get around legislation that sets a minimum size of 13sq metres for double rooms in Northern Ireland hotels.
The Belfast easyHotel has 81 rooms, many below regulation size.
Legislation for guest houses stipulates only that rooms should be "of adequate size for the number of visitors the room is intended to hold".
All accommodation must be certified by Tourism Northern Ireland, with requirements set out in the Categories of Tourist Establishment (Statutory Criteria) Regulations (Northern Ireland) 1992.
Operating without official approval is punishable by a fine of up to £2,500 or imprisonment of up to six months.
Tourism NI has been asked for a statement on the certification of easyHotel, but did not immediately respond.
The accommodation is in a converted office building on Howard Street.
The project cost £5m.
In a statement, easyHotel said it had opened "ahead of schedule following receipt of certification" and that there has been "strong momentum" in bookings.