Vietnamese human rights bloggers and activists are being beaten and intimidated, Human Rights Watch said in a report released Monday, as it urged the communist government to end attacks and hold those responsible accountable.

The New York-based rights group described 36 incidents in which unknown men in civilian clothes beat rights campaigners and bloggers between January 2015 and April this year, often resulting in serious injuries.

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