HONG KONG — The head of an international human rights group who had planned to criticize China’s growing global influence at an event in Hong Kong said he was barred from entry on Sunday in the latest sign of eroding freedoms in the city.

Kenneth Roth, executive director of Human Rights Watch, said he was turned away at Hong Kong International Airport after arriving from New York. Mr. Roth had planned to release a report by his group on Wednesday spotlighting repressive governments around the world, with a lead essay on what he described as China’s deepening assault on international human rights efforts.

The barring of Mr. Roth, an American, from Hong Kong follows similar entry bans on a handful of journalists and human rights observers in recent years, raising concerns in a city that has long prided itself on upholding the democratic values of freedom of speech and information.

Hong Kong has been roiled by more than seven months of antigovernment protests rooted in anger at the encroachment of Chinese power on the semiautonomous territory. The local government is under pressure from the authorities in Beijing to restore order as well as defend its image abroad.