The United States on Friday condemned a Hong Kong court verdict that found 14 democracy campaigners guilty of subversion under a Beijing-imposed national security law.

"The defendants were subjected to a politically motivated prosecution," a US State Department spokesman said.

"In response, the Department of State is taking steps to impose new visa restrictions on PRC (China) and Hong Kong officials responsible for implementing the National Security Law."

The court in Hong Kong convicted 14 people on Thursday for organizing an unofficial election in 2021 with the goal of paralyzing the government, while two defendants were acquitted.

The US spokesman urged "authorities to uphold Hong Kong’s judicial independence, cease the use of vague national security laws to curb peaceful dissent, and restore the openness that was so crucial to Hong Kong’s vitality and competitiveness."

Hong Kong's government earlier hit out at "smearing" from some Western nations, foreign media and those dubbed anti-China groups and politicians.

Britain, Australia and the European Union were among those who also raised concerns over the verdict, which capped off the biggest prosecution yet against opposition figures in Hong Kong.

Beijing imposed the legislation on Hong Kong in 2020 after the city saw huge and sometimes violent democracy protests.