The leader of a new political party that did well in Thailand's election last month has appeared at a police station to face charges of sedition.
Scores of supporters greeted Thanathorn Juangroongruangkit, the leader of Future Forward, at the Bangkok offices.
Mr Thanathorn says an allegation, from 2015, that he aided a protest leader is politically motivated.
The ruling military and an opposition coalition are both vying to form the next government following the polls.
Who is Thanathorn Juangroongruangkit?
At 40, he is the young and charismatic head of the Future Forward Party, which has appealed strongly to young voters and opposes the military government, which has been in charge of Thailand since 2014.
Future Forward did well in March's election, finishing a strong third, gathering 6.2 million votes.
It has since joined a "democratic alliance" to try to prevent the 2014 coup leader and current Prime Minister Prayuth Chan-ocha from staying in power.
What are the charges against him?
They date back to 2015 and allege Mr Thanathorn gave assistance to the leader of anti-coup protesters, who violated laws on crowd gatherings.
Mr Thanathorn is accused of breaking three articles of the Thai criminal code and could face up to nine years in prison if found guilty.
He could also be disqualified from parliament.
The charges have been filed by an officer in the government.
Commenting on the delay in bringing the charges, police said there had been several reshuffles of personnel.
Mr Thanathorn is also facing a cybercrime charge for allegedly spreading false information.
What has Mr Thanathorn said?
Earlier in the week he said the charges were politically motivated, adding: "The dark influence will not leave Future Forward Party alone."
As he left the police station on Saturday, he asked: "Why does this come a week after the election?
"We believe in our innocence, This isn't about me. This is about everyone who fights for justice."
Scores of supporters, many wearing the party's orange colour, shouted slogans backing Mr Thanathorn.
They held up posters with the trending #SaveThanathorn hashtag and slogans such as "end the age of the dinosaur".
What has happened since the polls?
The election results are not scheduled to be ratified until 9 May.
Preliminary results suggest the party backing Gen Prayuth won the most popular votes, ahead of the Pheu Thai party, which is allied with exiled former PM Thaksin Shinawatra.
But a complicated system of allocating seats in parliaments based on vote share, introduced by the military, means it remains unclear how many seats each party will ultimately have, hence the uncertainty on the next government.
The BBC's South-East Asia correspondent, Jonathan Head in Bangkok, says the Election Commission has been indicating that fewer seats than expected will be given to Future Forward and Mr Thanathorn's supporters view the latest criminal charge against him as part of a wider campaign to keep his party out of power.