Thailand's king has returned to a Bangkok hospital, after making a brief public appearance to attend a ceremony at the royal palace held to mark his 82nd birthday.

King Bhumibol Adulyadej, the world's longest reigning monarch who is a unifying force in a politically fractured nation, was lifted in his wheelchair out of a van and pushed back into hospital, Thai television showed.

He spent about one hour out of the hospital wing where he has been staying since being admitted on 19 September with a lung infection and fever.

He has appeared twice in public since then to be met by thousands of Thais, many of whom who regard the monarch as a demi-god.