A Thai court on Wednesday acquitted five anti-government protesters indicted on charges of attempted violence against the country's queen during a demonstration in 2020, a legal aid group said.

The case stemmed from an event at the height of pro-democracy demonstrations in 2020, in which a motorcade carrying Queen Suthida was heckled as it drove past a group of protesters.

The youth-led demonstrations had also called for royal reform including amending the controversial lese majeste law, which punishes each perceived royal insult with up to 15 years in prison.

The monarchy, which many Thais consider sacrosanct, is officially above politics and constitutionally enshrined to be held in "revered worship".

Video footage of the October 2020 incident showed authorities pushing activists away from the convoy.

"The court saw that police did not clear the way for the royal motorcade ... there was no announcement before the procession," Thai Lawyers for Human Rights said on Wednesday.

"Witness testimony was different and even police in the area did not know there would be a royal motorcade (passing through)," the group said.

The court did not immediately respond to a request for comment.

Five activists had been indicted under a law that punishes violence or attempted violence against the queen, heir-apparent or regent with a minimum sentence of 16 years in prison.

More serious breaches of the same law can lead to life imprisonment or a death sentence.

"I'm really glad ... we've been fighting this and insisting on our innocence," activist Bunkueanun "Francis" Paothong, 23, told Reuters by phone after the verdict.

(Reuters)

The royal motorcade carrying Thailand's Queen Suthida and Prince Dipangkorn drives past a group of anti-government demonstrators in front of Government House, on the 47th anniversary of the 1973 student uprising, in Bangkok, Thailand October 14, 2020. (Reuters)

Thai protesters acquitted over run-in with queen's motorcade