By Reuters HANOI - Vietnamese human rights activists and independent media groups have written to Mark Zuckerberg, Facebook Inc’s chief executive, questioning whether the social media platform was helping suppress dissent in the communist country. The letter, released on Tuesday by U.S.-based human rights group Viet Tan and signed by nearly 50 other groups, said Facebook’s system of automatically pulling content if enough people complained could “silence human rights activists and citizen journalists in Vietnam”. A Vietnamese Facebooker and a human right activist La Viet Dung shows the open letter signed by himself sent to Facebook Inc.'s chief executive Mark Zuckerberg, in Hanoi, Vietnam April 10, 2018. (REUTERS/Kham / MANILA BULLETIN) Despite sweeping economic reform in Vietnam, and increasing openness toward social change, including gay, lesbian and transgender rights, the ruling Communist Party retains tight media censorship and does not tolerate criticism.Vietnam last year unveiled a 10,000-strong military cyber warfare unit, named Force 47, to counter “wrong” views on the internet. The open letter to Zuckerberg called Force 47 “state-sponsored trolls” and accused them of exploiting Facebook’s community policies and disseminating fake news about the activists. Vietnam’s government said Facebook has committed to work with it to prevent content that violates the country’s laws from appearing on its platform and will also remove fake accounts and fake content about senior government officials. The activists said the frequency of takedowns had risen and Facebook’s has been unhelpful in restoring accounts and content, after its Head of Global Policy Management Monika Bickert met with Vietnamese Information Minister Truong Minh Tuan in 2017. Facebook said at the time of the meeting it would set up a separate channel to directly coordinate with the communication and information ministry on reports of illegal content. “We appreciate Facebook’s efforts in addressing safety and misinformation concerns online in Vietnam and around the world,” the activists said. “Yet it would appear that after this high profile agreement to coordinate with a government that is known for suppressing expression online and jailing activists, the problem of account suspension and content takedown has only grown more acute.” Earlier this month, Vietnamese human rights lawyer and activist Nguyen Van Dai was jailed for 15 years on the charge he “aimed at overthrowing the people’s administration”. Another five activists were jailed for seven to 12 years. Their sentences prompted responses by representatives from the United States, the United Kingdom, Germany, the Netherlands and the European Delegations among other rights groups. But Vietnam’s foreign ministry spokeswoman Le Thi Thu Hang said “there is no such thing as people being arrested for freely expressing opinion” in Vietnam. Facebook had not immediately response to a request for comment on the letter to Zuckerberg. Vietnam’s ministry of foreign affairs did not immediately responded.