Having issued an open letter June 14 calling for his release, Ching's friends went further Wednesday by launching a petition drive in their attempt to secure freedom for the 55-year-old, who was formally charged with spying Friday after being held in the mainland since April 22.

Among the 150 friends and former classmates at the launch were legislators Audrey Eu and Cheung Man-kwong, Hong Kong University pollster Robert Chung and political academics, Anthony Cheung and Joseph Cheng.

Mak Chai-ming, who attended Hong Kong University with Ching and has known him for more than 30 years, said he did not find the spying allegations to be credible.

``We all know him so well as a very honest and patriotic person who is devoted to his ideal of serving the country,'' he said.

``Ching is not a greedy man. The accusations are very puzzling and hard to believe.''

Solicitor David Hui, who was Ching's student when he taught geography in high school in the early 1970s, described his former teacher as down-to-earth and prudent.

He said the mainland authorities' treatment of Ching is grossly unfair and that they have never given the journalist a chance to defend himself.

``Although Ching has been detained for more than 100 days, a report alleging he had an affair with a mainland woman emerged immediately after his arrest. Such a coincidence is very abnormal,'' said Hui.

A secondary-school classmate, Paul Lai, said the arrest has prompted another friend of Ching's to consider leaving Hong Kong.

``I can understand his worries,'' he said. ``Suppose someone has to deal with both Taiwan and China in their work or business - that person could face a situation similar to Ching's.''

Xinhua News Agency said Friday the National Security Bureau has formally charged Ching with spying for Taiwan since 2000, claiming he had used the alias of Chen Yuan-chun and had obtained ``a great deal of information about China's political, economic and military affairs, including some classified as top secret or confidential, and passed it on to Taiwanese intelligence.''

Xinhua claimed Taiwan intelligence officers had given Ching several million Hong Kong dollars to fund his espionage activities.

Only a few of Hong Kong's pro-Beijing newspapers carried the story alleging Ching had an affair with a 42-year-old mainlander surnamed Huang, a former publishing editor in Shenzhen.

The reports said the journalist was meeting Huang when he was arrested in Guangzhou April 22, contradicting claims by Ching's wife, Mary Lau, that he was receiving an interview transcript relating to former premier Zhao Ziyang, who died in January this year.

The reports also claimed that in 2000 an agent commissioned Ching as a freelance writer for the Foundation on International and Cross-Strait Studies - a Taiwan organization with close links to Taipei's National Security Bureau.

Ching was paid up to HK$100,000 per report, it was alleged. But the agent gradually asked Ching to provide more in-depth information about the mainland, which was handed over to Taiwan's spy masters.

Mak and Hui called for an open trial and for Ching to be freed as soon as possible if he is proved innocent.

National People's Congress local deputy Tsang Hin-chi said Wednesday such a trial is unlikely. ``As the case involves state secrets, it's very clear these cannot be publicized,'' he said.

Democratic Alliance for Betterment and Progress of Hong Kong legislator Tsang Yok-sing said the key point in the case lies in whether mainland authorities have any concrete evidence to support their allegations.

He hoped Beijing will disclose more concrete facts and detailed information.

Ching's friends have created a Web site at www.chingcheong.com to provide more information on the case and to build public support for the journalist.

michael.ng@singtaonewscorp.com