Thai authorities are looking for the source of a new set of messaging stickers apparently making fun of the Thai royal family that appeared in the sticker store of popular app Line.

Thailand has very strict lèse-majesté laws that can convict anyone who insults or makes fun of the Thai royal family.

"We are investigating where the stickers came from and who did this," Colonel Somporn Daengdee, deputy chief of the police's Technology Crime Suppression Division, told Reuters.

Journalist Andrew MacGregor Marshall managed to capture the stickers, which have since been pulled from the messaging app's store.

Some interesting new Thai royal-themed LINE stickers that I found online. You can download them here:... Posted by Andrew MacGregor Marshall on Wednesday, April 6, 2016

Image: Andrew MacGregor Marshall/facebook

Image: ANDREW MACGREGOR MARSHALL/FACEBOOK

Line allows people to submit sticker sets to its store, which are screened by staff at the head office in Japan for offensive content.

However, people unfamiliar with stories about the Thai royals might not immediately recognise their depiction in the sticker set. As such, it's likely that they slipped past Japanese staff vetting submissions to the store.

But if you know the stories, you might spot the likeness of the crown prince who loved his poodle, Air Chief Marshal Foo Foo, or his sister Princess Maha Chakri Sirindhorn, who's known for contributing arts and craft work to the community.

A source sent Mashable a statement from people who say they created the stickers. Their location or identity couldn't be confirmed. "In Thailand, reverence for the royal family has sometimes been exploited to silence political debate. We wanted to create some light-hearted stickers that show the Thai royals as just like any other family. The furious reaction of Thai police shows Thailand is still far from democracy and freedom of speech," they said.

Line quickly issued an apology after removing the sticker set.

LINE Corporation is aware of the culturally sensitive sticker set that may have caused discomfort among our users in... Posted by LINE Global on Wednesday, April 6, 2016

Line has a reported 33 million users in the kingdom, making up the majority of Thailand's mobile population. It is one of Line's largest markets in Southeast Asia.

This isn't the first time Line has had to pull stickers that rubbed authorities the wrong way in the region.

In February, it removed stickers with LGBT content from Indonesia's sticker store, at the apparent behest of the government there.

The punishment for the sticker maker of the Thai set is likely to be harsh, if the person or group resides in Thailand. Last year, a man was arrested for allegedly insulting the king and the monarch's beloved dog. He was charged with two counts of violating the lèse-majesté law — one for the king, and the other for the dog — which could land him 32 years in jail.

UPDATE: April 7, 2016, 11:55 a.m. BST

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