Chinese authorities are holding an Australian writer, who used to be a Chinese citizen, on suspicion of endangering state security, China said on Thursday, and his lawyer said he was suspected of espionage.
Australian officials said Yang Hengjun was detained shortly after he flew in to the southern city of Guangzhou from New York last week, but it did not believe his detention was the result of rising tension between China and the West.
Chinese foreign ministry spokeswoman Hua Chunying said that Australia was officially notified after Yang was placed under "coercive measures" - a euphemism for detention - in Beijing.
"The Australian citizen Yang Jun, due to being suspected of engaging in criminal acts that endangered China's national security, was recently placed under coercive measures and is being investigated by the Beijing city State Security Bureau," Hua told reporters.
Yang's rights and interests were being protected in accordance with the law, she told a regular news briefing in Beijing, using a slightly different name for him.
Australian Defence Minister Christopher Pyne, who arrived in Beijing on Thursday for scheduled talks, said Australia would normally expect to be told of such a case within three days under existing diplomatic conventions.
Yang went missing on Friday and Australia was not told until four days later. Pyne said the late notification was disappointing and he would be raising it in his talks with Chinese officials.
"He's being held in residential surveillance," Pyne told reporters.
The Australian government was first alerted that Yang had gone missing after friends said he had been out of contact for several days.
Yang's lawyer, Mo Shaoping, told Reuters that his client was suspected of "espionage", and was being held under "residential surveillance at a designated location".
The special detention measure allows authorities to interrogate suspects for six months without necessarily granting access to legal representation. Rights groups say that the lack of oversight raises concern about abuse by interrogators.
Mo said he had been retained by Yang's wife but because the case involved state security, he would need approval from the authorities before he would be able to meet Yang.