A billionaire Thai opposition figure was indicted and granted bail on Monday after being charged with violating the country’s tough royal defamation laws, in the highest profile lese majeste case yet.

Thanathorn Juangroongruangkit was charged last year after he posted a video in which he questioned whether Thailand was leaning too heavily on Siam Bioscience – closely linked to the Thai royal family – for its vaccination campaign.

The 43-year-old, who founded the now-banned and hugely popular anti-establishment Future Forward Party, also faces charges relating to computer crimes.

On Monday, a judge ruled that the court would indict Thanathorn for leste majeste, which can carry a sentence of 15 years imprisonment per charge, and granted bail to the billionaire with a 90,000 baht ($2,600) guarantee.

Speaking outside the court, Thanathorn said he believed the case was “politically motivated” and vowed to contest the charges.

“It is clear that I am one of the key opposition [figures] and I think the objective is to silence me, to make the public afraid. So if we can keep silent, keep our mouths shut, they win,” he said.

Thanathorn is the highest profile individual to be hit by recent lese majeste allegations.

He joins a raft of activists who have also been charged since a pro-democracy movement rose up in 2020 – with some of the most prominent calling for controversial royal reforms.

Before it was disbanded, Thanathorn’s Future Forward Party was Thailand’s third largest, drawing millions of supporters who were attracted to his anti-establishment platform during the 2019 election.

But they were felled by swift legal action, which saw its top executives, including the young billionaire, banned from politics and the party dissolved.

Siam Bioscience is owned by the Crown Property Bureau, which manages the royal family’s multi-billion-dollar fortune.