A prominent Thai democracy protest leader facing royal defamation charges was granted bail on May 11 amid deteriorating health following a hunger strike that lasted more than 50 days.

Parit Chiwarak, who goes by the nickname "Penguin", had been remanded in custody since March when authorities indicted him under Thailand's strict lese-majeste laws.

Late last month, he was transferred to hospital after losing 12kg.

The university student faces 20 lese-majeste charges for his role in last year's demonstrations against the Thai government, which called for reforms to the country's monarchy.

On May 11 a criminal court granted Parit bail.

"Parit has made a statement with free will that if he gets bail he will not carry out any action to dishonour the monarchy and will not attend any activity causing unrest. He will not leave the country unless the court gives permission," the court said.

Late on May 11 night he left the Klong Prem maximum security prison in an ambulance, accompanied by his mother, and wearing a T-shirt emblazoned with "monarchy reform".

He gave a three-fingered salute – a symbol of resistance – out the window of the vehicle, which was expected to take him to a Bangkok hospital for further medical treatment.

Before his release he was hit with a further arrest warrant for a separate criminal charge, but was granted bail.

Musician Chaiamorn Kaewwiboonpan was also granted bail over two royal defamation charges he faces.

He also gave a three-finger salute as he was driven away from the prison.

A bail hearing on May 11 for a third activist – Panupong "Mike" Jadnok, who is facing eight royal defamation charges – has been postponed because he is at risk of developing a coronavirus infection after coming in close contact with a positive case.

Eighty-six people from the democracy movement have fallen foul of Thailand's royal defamation laws since July last year and are awaiting trial.

Those convicted can be sentenced to up to 15 years in jail per charge.

Student-led protests in Bangkok last year drew tens of thousands of people at their peak but the near daily rallies have petered out as Thailand grapples with a third wave of coronavirus infections and tighter restrictions on public gatherings.

Another student leader, Panusaya Sithijirawattanakul, more commonly known by her nickname Rung, was freed from custody last week.

She faces nine charges of insulting the monarchy.

Another high-profile protest leader, human rights lawyer Anon Numpa, who is facing 12 charges, has been unable to apply for bail while he recovers from a coronavirus infection in hospital.