In a rare gesture, Thailand's king has been shown on video praising a man who supported the monarchy at an anti-government protest.
King Maha Vajiralongkorn thanked the man, who had held up a portrait of his late father.
Correspondents say this gesture may be a royal endorsement for those willing to come out and support the monarchy.
The monarchy has not previously commented on protests that have begun to raise questions about its role.
What did the king say?
King Vajiralongkorn lives more in Germany than in Thailand and when he is in Bangkok he typically presides over formal occasions in which there is little opportunity for interaction with ordinary people, the BBC's Jonathan Head reports from Bangkok.
But he broke that custom on Friday night, coming out from a temple ceremony with Queen Suthida, spending some time with a crowd of well-wishers, and speaking to a few of them.
He thanked a man who had held up a portrait of the king's late father during an anti-government rally.
ทรงมีพระปฏิสันถารกับประชาชนผู้ซึ่งเป็นบุคคลที่ชูพระบรมฉายาลักษณ์ในหลวง ร.9 ไว้เหนือหัวที่หน้าเซ็นทรัลปิ่นเกล้า ในวันที่มีการชุมนุมเมื่อวันที่ 21 ต.ค.ที่ผ่านมา โดยพระบาทสมเด็จพระเจ้าอยู่หัว ตรัสว่า "ขอบใจมาก..กล้ามาก..เก่งมาก" pic.twitter.com/o5BpTHUYMQ— เรารักพระราชวงศ์ (@ThaiRoyalFamily) October 24, 2020
"Very brave, very brave, very good, thank you," the king says to him in a video circulated widely on social media.
The monarchy is officially held to be above political disputes, and the palace has until now said nothing about the protests, our correspondent says.
What has the reaction been?
The brief interaction has drawn a big response in Thailand.
Royalists including Warong Dechgitvigrom, leader of the Thai Pakdee (Loyal Thai) group, said it was a touching moment that illustrated the king's care for the people.
But protesters said the king's comment had made his opposition to them clear. The #23OctEyesOpened hashtag has now been tweeted more than half a million times.
Why are people protesting in Thailand?
The student-led movement is demanding the resignation of Prayuth Chan-ocha, a former general who seized power in a 2014 coup and last year became prime minister after a controversial vote.
The protesters want a new election, amendments to the constitution and an end to the harassment of state critics.
They are also questioning the monarchy's powers, which has led to unprecedented public discussion of an institution shielded from criticism by law.
Thailand's lese-majeste law, which forbids the insult of the monarchy, is among the strictest in the world.
The protests have been largely peaceful for three months, but royalists may now feel emboldened to come out and confront the student-led reform movement after the king's comments, raising the risk of clashes between the two sides, our correspondent reports.