A court in Vietnam’s Ho Chi Minh City sentenced five activists to up to 15 years in prison on Friday after finding them guilty of running a political group that worked to overthrow the country’s one-party communist rule. The official Vietnam News Agency said group leader Luu Van Vinh was convicted of attempting to overthrow the “people’s administration” and sentenced to 15 years in prison in the one-day trial. It said four others received sentences of eight to 13 years on the same charges. They were also given three years of house arrest after their release from prison. The agency said Vinh was leader of a “reactionary organisation called the Vietnam National Coalition” that criticised, tarnished and distorted the policies of the Communist Party and state with the intent of abolishing the party’s leadership and overthrowing the government. It said the group was formed in October 2016, and the five were arrested three weeks later at its official launch. “The defendants’ acts directly infringed on the national security and the people’s interests,” the agency quoted the judges as saying. It said Vinh and another defendant denied the charges, but there was enough evidence to convict them based on confessions by other defendants, testimonies of witnesses and evidence collected by investigators. The defendants’ acts directly infringed on the national security and the people’s interests Vietnamese judges International human rights groups called for their release. “This cruel and senseless ruling is clearly aimed at stifling people’s right to speak their mind,” Minar Pimple, Amnesty International’s senior director for global operations, said in a statement on Friday. “Thirteen people have been placed behind bars in only the past five weeks for ‘crimes’ such as blogging, using Facebook and other peaceful pursuits. This is a deeply concerning escalation,” he said, adding that there are over 100 other “prisoners of conscience” in Vietnamese prisons. Vietnamese communist authorities tolerate no challenge to their one-party rule despite sweeping economic reforms since the mid-1980s that opened up the country to foreign trade and investment and made it one of the fastest growing economies in the region.