Vietnam has released dissident Nguyen Ngoc Nhu Quynh from prison. She left the country immediately on a flight to the United States, said people with direct knowledge of the situation.

Quynh, known as "Mother Mushroom," is one of Vietnam's most famous dissidents. She was serving a 10-year prison sentence for spreading anti-government propaganda.

One person with knowledge of her case told Reuters that Quynh was not alone. "She is flying with her children and mother," the person said.

FILE - Nguyen Ngoc Nhu Quynh, center, a prominent Vietnamese blogger known as "Mother Mushroom", stands trial in the south-central province of Khanh Hoa, Vietnam on Nov. 30, 2017. (Tien Minh/ Vietnam News Agency via AP, File)

Vietnam's foreign ministry did not immediately answer a request for comment.

The U.S. Embassy in Vietnam did not answer questions from the Reuters news agency. It told Reuters to contact the Vietnamese government. Quynh's mother could not be reached by telephone.

News of the release came shortly after U.S. Defense Secretary Jim Mattis left Vietnam. It was not known if the release had any connection with his visit.

Mattis arrived there on Tuesday and left for Singapore on Wednesday. A Defense Department spokesman did not comment when asked about the timing of the release.

Vietnam has made a number of economic reforms and had been increasingly open towards social change in the country. However, the ruling Communist Party does not permit criticism that it considers threatening to its rule.

Nguyen Ngoc Nhu Quynh is a blogger and environmental activist. She was among 13 women to receive an International Women of Courage Award last year from the U.S. State Department. President Donald Trump's wife, Melania, presented the awards at a ceremony in Washington.

Mother Mushroom was arrested for publishing what police described as anti-state reports on the internet. One message talked about civilians dying while under police control.

She was sentenced last year in a government campaign against dissidents. It began in 2016 when more conservative leaders gained top Communist party positions.

Quynh is the second dissident released this year. Vietnam freed human rights lawyer Nguyen Van Dai in June. He went to Germany.

Nicholas Bequelin is with the rights group Amnesty International. He says Vietnam is requiring dissidents to promise to leave the country in order to get out of prison.

"While Mother Mushroom is no longer imprisoned, the condition for her release was exile," he said. He added that more than 100 people remain in Vietnamese jails because they peacefully expressed their opinions, in public, on blogs and on social media.

The Reuters news agency reported this story. Caty Weaver adapted it for VOA Learning English. George Grow was the editor.

_______________________________________________________________