A court in Hanoi last week sentenced Nguy Thi Khanh, 46, to two years in jail.

The US state department said it was “deeply concerned” by the sentencing and called for her release.

Vietnam’s foreign ministry spokesman Le Thi Thu Hang said today, Khanh “was investigated and prosecuted for economic offences regarding tax evasion and she admitted her wrongdoing”.

“Comments saying that Khanh’s arrest and verdict was due to her environmental campaigns are groundless and do not reflect the nature of this case,” Hang said.

A lawyer for Khanh did not answer calls for comment on the case.

Before her arrest in January, Khanh called into question Vietnam’s pledges at the United Nations COP26 climate summit last year, when prime minister Pham Minh Chinh vowed to achieve net-zero emissions by 2050.