HONG KONG — Prosecutors in Singapore have charged an activist with holding unauthorized public assemblies, which human rights groups have criticized as an excessive restriction on free speech.

Jolovan Wham, 37, was accused of organizing three small gatherings over the past year, including one that featured Joshua Wong, the Hong Kong democracy advocate, speaking by Skype. The authorities say Mr. Wham did not receive a police permit for the gatherings, a violation of the city-state’s Public Order Act that is punishable by fines of up to $3,715 for a first offense.

Singapore has strict limits on speech and unauthorized public assembly, even for political gatherings that are small and peaceful. Free speech organizations say such laws are far too harsh.

“Prosecuting Jolovan Wham for holding peaceful gatherings demonstrates the absurdity of Singapore’s laws on public assemblies and the government’s willingness to penalize those who speak out,” Phil Robertson, deputy Asia director of Human Rights Watch, said in a statement. “The Singapore government should start listening to criticism, stop treating peaceful assemblies as crimes and cease prosecuting their organizers.”