Bangkok (AFP) - Thailand's crown prince led a mass cycle in Bangkok Friday at a symbolic event to honour his father King Bhumibol Adulyadej and highlight his role as heir apparent amid increasing anxiety over his dad's health.
Clad in lycra, a helmet and sunglasses, Prince Maha Vajiralongkorn, 63, headed the cyclists at the "Bike for Dad" event -- a rare public appearance for the prince -- which follows a similar event in August for his elderly mother Queen Sirikit.
The mass cycles, broadcast live on every Thai television channel, have been billed as a chance to promote unity among Thais 18 months after a coup swept away the civilian government -- the latest episode in a seemingly endless succession of elections and coups.
They also give the twice-divorced prince a chance to bolster his image, promoting himself as a dutiful son, and crucially, that he has the strong backing of the armed forces, who joined him at the event.
"I am delighted that the Crown Prince graciously inaugurates the 'Bike for Dad'... to honour the King on his 88th birthday," coup-making army chief turned premier Prayut Chan-O-Cha said.
- Prince centre stage -
Prayut and top military and political leaders, all clad in yellow in a nod to the King's official colour, followed the Prince among an expected 100,000 cyclists on a 29-kilometre (18-mile) route through the capital.
Nationwide, more than half a million people are expected to take part, topping the 136,411 people at the "Bike for Mom" cycle.
"I am happy to stop work because I love the king. With all my heart I wish the king good health," said Supab Jarupoom, a 68-year-old butcher from Bangkok, wearing a Thai flag headband and with a photo of the King on his bicycle.
The king is revered among many Thais but has been in hospital for much of the last two years and is rarely seen in public.
Vajiralongkorn has yet to attain such popularity and his ability to operate as a unifying force ostensibly above the political fray is untested.
In recent years, the crown prince has spent much of his time away from the public eye. But he has stepped in at some official ceremonies as his father's health declines.
The cycling events have thrust Vajiralongkorn centre stage at a time of heightened concern over his father's health and country's future.
"Though the activity intends to praise the king as father of the nation, some might interpret the activity as bestowing greater monarch-to-be legitimacy upon the crown prince," Thai politics expert Paul Chambers told AFP.
For much of the last decade Thailand has been rocked by political instability partially fuelled by jostling among the country's elites for influence as the king's reign enters its twilight years.
Bhumibol and his family are protected by one of the world's harshest lese majeste laws, making criticism of the monarchy or public debate about its role in society all but impossible.
Prosecutions have surged since last May's coup, with a Thai man arrested this week for 'liking' a doctored photo of the King.