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, with Washington also announcing visa restrictions.

The court had 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 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 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."

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

The Hong Kong government on Friday expressed "strong dissatisfaction and condemnation" of the planned visa restrictions.

The move "smacks of despicable political manipulation... violating international law and the basic norms governing international relations," a spokesperson said.

"(Hong Kong) despises any attempts at interference and is not intimidated."

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.

UN High Commissioner for Human Rights Volker Turk called for the "release immediately and unconditionally (of) all those arbitrarily arrested and detained" under Hong Kong's national security laws.