HANOI - Vietnamese police have detained a prominent blogger for posting anti-state reports, including one about civilians dying in police custody, which they said undermined trust in the ruling Communist Party.

Nguyen Ngoc Nhu Quynh, 37, known as "Me Nam" (Mother Mushroom), was held Monday in her home city of Nha Trang in the central province of Khanh Hoa for running "propaganda" against the state, the provincial police said Tuesday in a statement posted on their website.

Despite sweeping reforms in Vietnam's economy and increasing openness toward social change, including gay, lesbian and transgender rights, the Communist Party retains tight media censorship and zero tolerance for criticism.

The statement said Quynh posted a report compiling 31 cases in which civilians had died in police custody, which showed "hostility towards the police force."

"We're not really surprised by this arrest. We knew this day would come," Quynh's mother, Nguyen Thi Tuyet Lan, told Reuters. "This is revenge against my daughter."

In March 2009, Quynh spent nine days in police detention for receiving funds from Viet Tan, a California-based activist group, to print T-shirts carrying slogans against a major bauxite project in the Central Highlands, police said.

The EU delegation in Vietnam called on Hanoi to release Quynh, saying "this arrest goes against the country's international and domestic human rights obligations."

The EU was criticized for refusing to carry out a human rights impact assessment before it concluded a free trade agreement with Vietnam last year.

Last week, Hanoi declared Viet Tan "a terrorist organization" and warned that any Vietnamese found to be involved with the group would be regarded as co-conspirators and punished.

Quynh had also spoken out against a subsidiary of Taiwan's Formosa Plastics Corp. that caused one of Vietnam's biggest environmental disasters in April.

State-run media has reported that a provincial court has rejected hundreds of lawsuits submitted by fishermen seeking to sue the subsidiary.

Vietnam has been accused of using vague laws to stifle bloggers and activists who are getting more exposure from the proliferation of social media in Vietnam, which has one of Asia's highest concentrations of Web users.

The Southeast Asian nation was holding at least 130 political prisoners at the end of last year, according to the New York-based Human Rights Watch.