BANGKOK — You must be only this wide to ride.

“Obese” passengers will no longer be allowed in Thai Airways’ business class on flights serviced by Boeing 787-9s, airline officials announced Friday, due to seatbelt limitations.

“Due to safety regulations, we reserve the right of booking tickets to passengers who have waists wider than 56 inches and passengers with lap-held infants,” said airline safety official Capt. Prathana Patthanasiri.

By obese, the airline means passengers with waistlines that exceed 56 inches, who cannot fit inside the seatbelts equipped in that jet’s business section. Those riding in the other classes can still be as wide as they please.

People planning to cradle their babies in business class must also opt for a coach ticket or pay for a baby seat instead since the new belts cannot accommodate lap-held infants.

Prathana said Thai Airways added two new Boeing 787-9s to its fleet in September that connect the capital to Auckland, New Zealand, and Taipei.

Thai Airways said it is complying with US Federal Aviation Administration regulations since business class seat belts on this model of plane are equipped with mandatory airbags.

Thai Airways said that obese passengers should consult booking staff to see if their particular flights allow them to sit in business class.