BANGKOK: Thailand's Princess Bajrakitiyabha Narendira Debyavati, the oldest child of King Maha Vajiralongkorn, has been hospitalised due to a heart problem and her condition has stabilised at a certain level, the royal palace said on Thursday.

Princess Bajrakitiyabha, 44, was taken ill after losing consciousness early on Wednesday in northeastern Nakhon Ratchasima province and was treated at a local hospital. She was flown by helicopter to Bangkok after her condition stabilised at a certain level, the palace said in a statement.