BEIJING, Jan 9 (AFP) - Three Australian members of the Falungong sect are believed to have been detained in China after they delivered a letter addressed to President Jiang Zemin and Premier Zhu Rongji expressing concern over the treatment of Chinese practitioners.

Ana Caterina Turcu and twin brothers Simon Vereshaka and Nicholas Vereshaka took their letter to the Beijing headquarters of the government's news agency, Xinhua, Sunday morning.

They had alerted foreign journalists on Saturday that they would be delivering the letter. Photographers and journalists at the scene saw the three go into the building, but did not see them come out.

They were asked to stay inside after they delivered their letter and police were later called in, a photographer at the scene said.

The three Melbourne residents were planning to catch a flight back to Australia on Sunday.

In a copy of the letter faxed to AFP, the Australians asked Jiang and Zhu not to misunderstand the spiritual group, which China outlawed in July.

"Falun Dafa (the teachings of Falungong) is not a political movement. Any individuals who show any interest in politics, fame and gain cannot be considered Falun Dafa practitioners," the Australians said.

They said they had benefitted from practicing Falungong and could not stand by as China continued to prohibit Falungong practitioners from practicing the group's meditation exercises.

"To sit at home and do nothing when we hear the name of Falun Dafa being slandered is not an option for us, because what Falun Dafa has given us can never be fully expressed in words," they wrote.

"So we will continue to uphold and protect the Dafa until this situation is rectified."

China has labeled the group an evil cult and has accused founder Li Hongzhi, a New York resident, of causing the deaths of more than 1,400 people by fooling them into believing they could cure their illnesses by following his teachings, without seeking medical attention.

The Australians asked the Chinese leaders to legalize the group and lift the ban on it being practiced. They vowed to continue appealing to the authorities.

Chinese officials refused to comment on the three Australians. An official at the Australian Embassy in Beijing said its staff would look into the case.

Falungong teaches Buddhist-style meditation and promotes health and strong moral values. It claims to have 100 million members worldwide, with 80 million in China.

China considers the group the biggest threat to political and social stability since the 1989 Tiananmen Square demonstrations. It was alarmed when 10,000 members held a protest in Beijing last April against the arrest of fellow members.