Tens of thousands of Thais crowded central Bangkok for a rare address by King Bhumibol Adulyadej as part of celebrations for his 85th birthday.

At least 200,000 people flooded the capital's historic district yesterday, December 5, 2012, with aerial television images showing a sea of yellow as supporters of King Bhumibol Adulyadej dressed up in the colour associated with his reign.

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.

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.

Click on to see the celebration of the world's longest reigning monarch for his 85th birthday.

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