Thailand’s 87-year old King Bhumibol Adulyadej has backed out of a public audience at the Grand Palace on his birthday today, citing advice from his doctors.  It comes amid royliasts’ growing concern about the health of the king.

“A team of royal physicians examined the King on Thursday evening,” read a statement from the Bureau of the Royal Household, “and agreed that he is not ready to grant a royal audience.”

Thousands of people had turned out at the palace, hoping to get a glimpse of the king.  He was last seen in public last month, has avoided many appearances, and recently underwent an operation to remove his gall bladder.

The health of the king could play a role in future instability in Thailand, which is still under martial law from a military coup in May.  Crown Prince Vajiralongkorn appears to be consolidating power as his father ails.  The prince has had seven of his wife’s relatives arrested, accusing them of misusing their royal status to amass vast wealth and carry out numerous abuses.  He stripped his wife’s family of their royal name, and is believed to be preparing to divorce Princess Srirasmi.