Obama paid tribute to the King as a “tireless champion” for Thailand’s development, praising his “unflagging devotion” to improving the lives of his subjects.

“His Majesty the King was a close friend of the United States and a valued partner of many US presidents,” Obama said.

“I had the honour of calling on His Majesty the King during my visit to Thailand in 2012, and recall his grace and warmth, as well as his deep affection and compassion for the Thai people.

“With a creative spirit and a drive for innovation, he pioneered new technologies that have rightfully received worldwide acclaim,” Obama said.

“His Majesty leaves a legacy of care for the Thai people that will be cherished by future generations.”