China says Falun Gong is a dangerous cult
Supporters of the group abroad said events were planned in Tokyo, Sydney and other cities.
Protesters in Hong Kong marched and meditated, lining up to form the Chinese characters for "Falun Gong is good."
Falun Gong, which China says is trying to overthrow the Communist Party, was banned on mainland China three years ago, although it is tolerated in Hong Kong.
The movement itself says it is simply a spiritual group that teaches exercise and meditation.
It was first introduced to China and the world on 13 May 1992 by Li Hongzhi, a former grain clerk and trumpeter who now lives in the US.
The date is also marked by Falun Gong supporters as Mr Li's birthday, though China's government says he was actually born on July 7 and changed the date to coincide with the birthday of Sakyamuni, the founder of Buddhism, to pretend he is a reincarnation of Sakyamuni.
'Unreasonable'
"We cause no harm," said Lam Chau-ping, a 35-year-old housewife who joined 200 Falun Gong members in a demonstration near Hong Kong's Victoria Harbour.
"Beijing's crackdown is completely unreasonable."
The Chinese authorities have been wary of potential protests by Falun Gong ever since it was surprised by a demonstration in April 1999, when 10,000 followers of the group massed near the Chinese leadership compound of Zhongnanhai. That protest led to China's ban on the movement.
Falun Gong accuses Beijing of detaining thousands of its followers, and supporters abroad say at least 400 people have died in the hands of the authorities.
China, for its part, says the movement is responsible for 1,600 deaths, saying its teachings have inspired members to commit murder or suicide. The media has waged a long-term campaign against the group.
'Possessed by demon'
On Monday, China's official media gave widespread coverage to the case of a Falun Gong follower in north-east China who throttled her nine-year-old daughter to death on 22 April, believing that she was possessed by a demon.
"It was Falun Gong that has killed my daughter," China's Xinhua news agency quoted the woman's husband as saying.
The media did not say why it had waited three weeks to report the girl's death.
Falun Gong remains legal in Hong Kong, and the territory has tolerated most Falun Gong activities, although it recently arrested 16 people, including four Swiss members, for alleged obstruction when they protested outside a government office in March.