Authorities in Vietnam arrested the director of an independent energy policy think-tank, in its latest crackdown on experts from the field of environment and ecology in recent years.

Ngo Thi To Nhien, director of the Vietnam Initiative for Energy Transition Social Enterprise, was arrested for allegedly appropriating internal documents relating to state-owned firm Electricity of Vietnam, according to the state media reports.

She was detained on 20 September, spokesperson for the ministry of public security To An Xo, confirmed on Monday.

The official denied that the grounds for arresting Ms Nhien were related to “environmental activism”.

Earlier reports claimed that the think-tank’s top official was detained on 15 September.

“The security investigation agency of Hanoi city police issued an arrest warrant to Ngo Thi To Nhien,” Mr Xo said at a press conference late on Saturday.

If charged, Ms Nhien faced up to five years in prison, according to Vietnam’s criminal code.

According to a rights group, she was detained without any official confirmation.

Ms Nhien is a prominent researcher in Vietnam and has worked with a number of international organisations, including the World Bank, the European Union, the United Nations and the Asian Development Bank. She was reportedly working on an implementation plan for the country’s just energy transition partnership (JETP) at the time of her arrest.

The $15bn project will push Vietnam to wean off fossil fuels and is funded by the G7.

While the immediate reasons for her arrests are not clear, Vietnam is one of the few remaining communist single-party states that tolerate no dissent, including on environmental issues.

Human rights advocacy group The 88 Project have claimed that she has been arrested for “unknown reasons”.

In 2022, Human Rights Watch said that more than 170 activists had been put under house arrest, blocked from travelling or in some cases assaulted by agents of the Vietnamese government in a little-noticed campaign to silence its critics.

Ms Nhien’s arrest comes just days after a Vietnamese climate activist was sentenced to three years in prison on charges of tax fraud.

Hoang Thi Minh Hong, 50, who headed the environmental advocacy group Change, which works on environment and climate issues, was also fined 100 million Vietnamese dong ($4,100) by a court in Ho Chi Minh City, the state-owned Viet Nam News reported.