(Corrects spelling of "pre-trial" in headline)

BANGKOK (Reuters) -A Thai political activist died in custody on Tuesday, the department of corrections said, and a legal aid group said she had been on a partial hunger strike during her pre-trial detention on charges including insulting the country's monarchy. Netiporn "Bung" Sanesangkhom, 28, was part of a small anti-monarchy group called "Thaluwang," a name that translates to "shattering the palace", which organised actions such as opinion polls questioning the monarchy's power and holding small gatherings seeking the release of the detained members. She had been jailed since January 26 this year. Initially Netiporn was held for one month on a contempt of court charge related to a scuffle with court guards in 2023, legal aid group Thai Lawyers for Human Rights said.

Her pre-trial detention was extended after a court revoked her bail from a separate royal insult case stemming from a protest in 2022, the legal aid group said.

While in detention, Netiporn refused to take food and water for a month as a protest against political activists not being granted bail. She started drinking water in late February, and then eating in April after she was sent to a prison hospital because of her deteriorating health, the legal aid group said.

Netiporn's heart "stopped suddenly" on Tuesday, the department said in a statement, and the medical team at the prison hospital tried to revive her before sending her to Thammasat University hospital where she was declared dead.

The department said the university hospital will conduct an autopsy to determine the cause of death.

Netiporn was facing seven court cases related to her activism, including two charges of lese majeste violations, or insulting the monarchy.

Thailand's lese majeste law, one of the strictest in the world, protects the palace from criticism and carries a jail sentence of up to 15 years for each violation.

More than 272 people have been charged with insulting the monarchy since 2020, with 17 of those currently jailed in pre-trial detentions, according to Thai Lawyers for Human Rights.

Two other activists from the Thaluwang group who have been held in pre-trail detention since February are also on hunger strikes.

Another two other members of the group have fled the country, and remaining members could not be reach for comment.

(Reporting by Panu Wongcha-um and Panarat Thepgumpanat; Editing by John Mair)