Lieutenant General To An Xo, spokesman for the Ministry of Public Security, said Nhien was detained on September 20 for appropriating an organization's documents.
Xo denied claims that she was arrested due to "environmental activism."
Duong Duc Viet, 44, senior specialist of the investment management committee of the National Power Transmission Corporation under EVN; and Le Quoc Anh, 39, head of the system analysis department of the Power Engineering Consulting 1 company, were also arrested on the same charge.
Since 2020, Nhien knew Anh and Viet had the right to access information and documents regarding the planning for power grid development policies of EVN, authorities said. Nhien then "legitimized the appropriation of documents" by signing labor and expert contracts with Anh and Viet.
Anh and Viet later supplied the documents to Nhien.
"These are internal documents, which are not allowed to be shared or publicized," Xo said.