HANOI: Vietnam’s state television issued a warning to the public to shun calls by “reactionary forces” to join protests over an environmental disaster it said was being exploited to try to overthrow the government. An 11-minute prime-time report on Vietnam Television (VTV) disclosed names and images of well-known dissidents and bloggers it said were trying to dupe the public and violently undermine the government, with support and funding from overseas groups. Although communist Vietnam has long sought to silence and discredit its critics the warning by the country’s biggest broadcaster of possible seditious activity was highly detailed and of an unusually long duration. It was carried by several other major state-run channels. “Their intention to abuse and disturb was revealed when many subjects called for using knives and petrol bombs to attack the functional forces and to overthrow the authorities,” the narrator of the VTV report said. “Many people may ask what kind of peaceful marches are they … Is this possibly a preparation for a riot and overthrow?” the voice-over asked. The warning came as protesters had tried to rally for a third successive Sunday to vent their anger at the government and a unit of Taiwan’s Formosa Plastics, a firm they blame for causing an environmental disaster and the death of large numbers of fish in central coast provinces in April. Tight security in Hanoi and Ho Chi Minh City prevented major rallies taking place, however, although some social media postings showed small groups of demonstrators gathering. A government investigation into the fish deaths is underway but its preliminary probe found no links to Formosa’s $10.6 billion coastal steel plant in Ha Tinh province. Experts said either a “red tide”, when algae blooms and produces toxins, or a release of dangerous chemicals by humans, could have been to blame. Prime Minister Nguyen Xuan Phuc has promised a thorough investigation and to bring to justice those found to be responsible.