Tens of thousands of Thais crowded central Bangkok on Wednesday for a rare address by King Bhumibol Adulyadej, the world's longest reigning monarch, as part of celebrations for his 85th birthday.
Television images showed a sea of supporters of the revered king, many wearing yellow symbolising Monday, the day of his birth, and waving royal and Thai flags.
At least 200,000 people were expected to attend the speech from a balcony at the Anantasamakom Throne Hall in front of the Royal Plaza in the capital's historic district.
Crowds lined the streets chanting "long live the king!" along the route of the royal motorcade as it made its way from the hospital where the king has lived for three years after suffering a respiratory illness in 2009.
Bhumibol, who has served for 66 years, suffered a minor brain bleed in July, but has since made several official appearances including meeting Barack Obama during the US president's visit to the country last month.
Thailand's Queen Sirikit was not among the members of the royal family accompanying the king on Wednesday.
Doctors treating the 80-year-old queen, who was diagnosed with a slight loss of blood flow to the brain after being taken ill in July, said she was too weak to attend the ceremony, according to a statement from the palace on Tuesday.
Any discussion of the royal family is extremely sensitive in politically-turbulent Thailand, where the palace has been silent over the organisation of the eventual succession.
Royal Plaza was the heart of anti-government demonstrations in November that saw clashes between police and protesters in the city.
The rally -- attended by members of the influential monarchist "Yellow Shirts" -- was the latest street unrest in Thailand's long-running political crisis pitting Thai royalists against supporters of ousted premier Thaksin Shinawatra and the current government led by his sister Yingluck.