A Thai Youtube presenter has apologised for criticising a Miss Universe pageant dress that was designed by the daughter of Thailand’s king.

Wanchaleom Jamneanphol, a popular online personality, also known as ‘Mixy Bigmouth’, reportedly made disparaging remarks about a blue dress worn by the Thai Miss Universe contestant and designed by Princess Sirivannavari Nariratana.

Jamneanphol’s comments went viral and Kitjanut Chaiyosburana, an aspiring politician contesting next year’s national election, told AFP news agency on Wednesday he filed defamation charges against her.

“I think internet idols are like an actor or actress with many followers… so if they commit wrongdoing online it should not end up with just apologies,” he said.

Under the country’s cybercrime and lèse-majesté laws – which make it illegal to say anything negative about the monarchy – this action could lead to criminal prosecution.

Local law dictates that any Thai citizen can file defamation charges on behalf of another person, and convictions can carry custodial sentences of up to two years.

The gown was worn by the entrant, Sophida Kanchanarin, at the 67th Miss Universe pageant which was held in Nonthaburi province, Thailand.

Princess Sirivannavari Nariratana, 31, who has a masters in design from a French university, created a range of swimsuits and two Thai silk evening dresses for the contest, which took place in Bangkok at the weekend. 

A Thai police spokesman confirmed that the YouTuber was under investigation but has yet to be formally charged, the Daily Mail reported.

Jamneanphol has since removed her original viral post, apologising for her comments on Monday night and saying she “did not have any intention to insult or disrespect the high institution”.

She also promised to think before publishing future social media posts.