The prominent blogger Me Nam, or “Mother Mushroom”, has accused the police of using violence to break up an attempt by activists to campaign for the freedom of political prisoners.
She said police attacked her and other activists as they attempted to participate in the campaign in the southern city of Nha Trang.
The blogger, whose real name is Nguyen Ngoc Nhu Quynh, said she was hit and suffered a bloody nose and mouth as she was dragged into a taxi by plainclothes police.
She was held and questioned for several hours before being released.
Human rights campaigners attempted to hold gatherings in cities across Vietnam, supported by similar rallies by overseas Vietnamese communities in the United States and Australia.
They called it a “one day hunger strike” to draw attention to the plight of the more than one hundred prisoners of conscience being held in Vietnamese jails.
The police were not available for comment and have made no statement about the accusations of violence.
“We had just put on our white t-shirts with slogans on,” said Me Nam.
“We were just starting to meditate in a park behind the beach when the security forces stepped in and slapped me,” she said.
She was bundled away into a taxi while some of the other campaigners also said they were assaulted.
One suffered a black eye in the melee with police.
Me Nam said she was dragged by the police through a crowded seaside area that is popular with foreign tourists.
She called out for help in English as she was put in the taxi.
The slogans on the shirts were calling for the release of fellow activists Nguyen Ngoc Gia, Bui Thi Minh Hang and Tran Huynh Duy Thuc.
The police had earlier used a loudspeaker to call on the group to disperse.
The protesters said the police seized memory cards and cameras to try to stop any pictures of the incident circulating, although they didn’t manage to seize them all.
The attempt to highlight the plight of political prisoners followed the sending of a letter to the Human Rights Council of the United Nations earlier this year.
Me Nam said it was the first time in 40 years that campaigners inside the country had linked up with Vietnamese abroad in such a way.