Thailand's King Bhumibol Adulyadej left hospital on Monday to visit his Bangkok palace, his first such outing since he was admitted last year.

His trip to the Chitralada Palace follows a Royal Household Bureau announcement on Sunday that the 88-year-old king was recovering from a blood infection and swollen lung.

King Bhumibol, the world's longest serving monarch, has been in hospital since May and has received treatment for multiple illnesses. Nervousness over his health and the succession has formed the backdrop to a decade of political crisis in Thailand, where the military took power in a coup in May 2014.