(BANGKOK): Two royal events were abruptly canceled Wednesday and the Thai junta chief has returned from a provincial trip amid deep worries about a sharp decline in the health of the country's 88-year-old king.

King Bhumibol Adulyadej — the world's longest reigning living monarch — underwent dialysis at the weekend, with a Sunday statement saying his condition has not yet stabilized and he would remain “under close medical supervision”.

There has been no further statement from the Royal Household Bureau since.

On Wednesday, Crown Prince Vajiralongkorn and Princess Chulabhorn — the eldest son and one of three daughters of the king — canceled respective appearances at an Oct. 27 graduation ceremony and at a royal decoration ceremony, according to statements posted by event organizers.

Khaosod daily reported that online flight records showed that Vajiralongkorn had flown to Bangkok from the German city of Munich, where he resides for much of the year.

Meanwhile, Kom Chad Luk newspaper reported that junta chief-cum-prime minister Gen. Prayuth Chan-ocha had cut short a ceremony to inaugurate a new military facility in Chonburi, east of Bangkok, to also return to the capital.

Since Monday, scores of Thais have been flocking to Siriraj hospital — where the king has been treated since 2009 — and Buddhist temples to pray for the ailing monarch.