The biggest concern, they said, was a new push by China in recent years to gather intelligence on military-related technology and strategic policy secrets.
"China would be the biggest now by a fair way," said one source, who said Chinese spies now outnumbered Russian agents who were previously Australia's biggest epsionnage concern.
"They have built up their capabilities over the last 10 years and are more aggressive in their activities," the source was quoted as saying.
China has one of the largest diplomatic corps in Australia, with 40 registered diplomats.
The new counter-espionage unit has been set up within the Australian Security and Intelligence Organisation (ASIO), the government's main intelligence agency, and is already operational, The Australian said
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and the US too ..
China has the great advantage of many ethnic Chinese all over the world and it is known they use them for intelligence. According to a new Pentagon report and China wathers, China is improving its far-flung system of human spies, recruits, sleeper agents and electronic eavesdropping in tandem with its build up of conventional military power. Since the mid-1980s China has developed the world's third- largest capability, after the U.S. and Russia, to intercept conversations and messages, according to the "Intelligence Threat Handbook'' distributed to Pentagon personnel.
China has a robust human spy system within the U.S.–– seven diplomatic establishments and 2,750 commercial offices in addition to an estimated 100,000 current and former students from the Peoples Republic, the handbook said. In addition, 27,000 PRC delegates visit the U.S. annually, it said.
Chinese intelligence makes an active effort to recruit Chinese-Americans, although “there is no evidence that the PRC considers Chinese-Americans to be more vulnerable to approach than any other group,” the book said.
“Chinese human intelligence operations rely on collecting a small amount of information from a large number'' of ethnic Chinese, it said. “The PRC attempts to recruit or at least ‘make friends' with as many Chinese-Americans as possible, apparently hoping that at least some will perceive an obligation to help China, perhaps on a confidential basis.''
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(as i've seen you post it on PDF) 
