Vietnam has arrested well-known environmentalist Hoang Thi Minh Hong for tax evasion, a government official said Thursday in the latest example of the Vietnamese government’s routine use of financial charges to imprison green activists.

The Ministry of Foreign Affairs’ deputy spokesperson Nguyen Duc Thang confirmed on Thursday to reporters that Hong, her husband, and two staff members were arrested the day before.

Hoang Thi Minh Hong is known for her activities in the fight against climate change, including bringing the Earth Hour initiative from Australia to Vietnam.

She is also famous for being the first Vietnamese woman to set foot in Antarctica in 1997, and in 2019, she was listed by Forbes magazine as one of the 50 most influential women in Vietnam.

Hong is the founder and executive director of CHANGE – a non-profit organization with the mission of inspiring the community and raising environmental awareness with the aim of protecting nature and wild animals, combating climate change, and promoting sustainable development.

Based on her activism, climateheroes.org included her in their 2015 “Climate Heroes” list. Four years later, in 2019, she was voted among the Top 5 Ambassadors of Inspiration at the 2019 WeChoice Awards and was named the Green Warrior of the Year at the Elle Style Awards.

Hoang Thi Minh Hong is the fifth activist in Vietnam to have been arrested on the charge of tax evasion.

International organizations and foreign governments have criticized Vietnam for targeting and detaining environmental activists and urged the Southeast Asian nation to release those who had been arrested on tax evasion charges.

Hong’s arrest came a week after a U.N. working group of independent human rights experts called on Vietnam to immediately release a detained climate activist serving a five-year prison term for tax evasion, saying he had been arrested arbitrarily and tried unfairly.

Lawyer and environmentalist Dang Dinh Bach, 44, who had campaigned to reduce Vietnam’s reliance on coal was arrested June 2021 and then sentenced to five years in jail.