Some ten thousand royalists turned out in Bangkok on Saturday for a drone show honouring the Thai king's late father, in a show of force by a monarchy under pressure following months of pro-democracy protests.

Since July demonstrators have made unprecedented calls to reform Thailand's monarchy -- a taboo-smashing demand in a country where the ultra-wealthy royal family has long been untouchable.

Thailand's King Maha Vajiralongkorn (C) greeted thousands of supporters in Bangkok on Saturday, at an event marking his late father's birthday
Thailand's King Maha Vajiralongkorn (C) greeted thousands of supporters in Bangkok on Saturday, at an event marking his late father's birthday AFP / Lillian SUWANRUMPHA

But Saturday saw the king's supporters turn out in force, wearing yellow and clutching portraits of royal family members as they gathered for a candlelight ceremony and drone display at the Sanam Luang field outside the Grand Palace in Bangkok.

Many chanted "long live the king" as they waited for Maha Vajiralongkorn and Queen Suthida, as well as Princesses Sirivannavari and Bajrakitiyabha and royal consort Sineenat "Koi" Wongvajirapakdi, to arrive in a golf buggy.

Thousands of royals turned out to honour the late Thai king Bhumibol Adulyadej, who died in 2016 and was widely revered in the country
Thousands of royals turned out to honour the late Thai king Bhumibol Adulyadej, who died in 2016 and was widely revered in the country AFP / Lillian SUWANRUMPHA

They were flanked by royal guards in red ceremonial costumes and bearskin-like hats.

"We are so upset (about the democracy protests)... because the monarchy is so deeply rooted in Thai culture. That is why we can not accept the young generation's behaviour and actions toward the king," Onnapa Malaisri, 44, told AFP.

Months of pro-democracy protests have sharpely divided Thais into pro and anti-royalist camps
Months of pro-democracy protests have sharpely divided Thais into pro and anti-royalist camps AFP / Lillian SUWANRUMPHA

Saturday marks the birthday of the late King Bhumibol Adulyadej, who died in 2016 and was widely revered in Thailand.

Tens of thousands of prisoners received royal pardons or had their jail terms reduced to mark the occasion, which falls on the same date as fathers' day in Thailand.

"It is the day we will remember and show appreciation to the greatest benevolence and kindness (the late King Bhumibol Adulyadej) showed us during his reign," the king said in a speech.

Some attendees cried as the late king's face was projected into the sky with synchronised drones.

But pro-democracy supporters took to Twitter questioning why fathers' day was linked to the monarchy, under a top trending hashtag.

The 68-year-old ruler sits at the apex of Thai power and analysts estimate the royal family's wealth to be between $50-$70 billion.

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