Insulting the monarchy, constitutionally enshrined to be held in “revered worship”, carries penalties of up to 15 years in prison under Thailand’s strict lese majeste law.

Tantawan “Tawan” Tuatulanon, 22, did a live broadcast on her Facebook account showing her arguing with police who were blocking cars for a motorcade carrying Princess Sirindhorn, the sister of King Maha Vajiralongkorn.

The incident triggered a public row that escalated into brawls on Saturday between ultra-royalists and monarchy-reform activists that left more than a dozen people injured.

Media reported that the car Tantawan was in was honking and trying to overtake the royal motorcade on a Bangkok expressway.

Tantawan has denied that her car was trying to harass or block the royal convoy. She and a colleague were arrested today.

Deputy police chief Surachate Hakparn said that honking at a royal motorcade and posting video online damages the monarchy. He said such action justified the sedition charge, punishable by up to seven years in prison.

Tantawan is already facing royal insult charges for previously discussing the royal motorcade issue.

A youth-led political movement that emerged in 2020 broke traditional taboos by calling for the reform of the monarchy and has previously criticised the blocking of traffic for royal motorcades.

Prime Minister Srettha Thavisin called yesterday for dialogue in “safe spaces” over royal family motorcades.