"They don't all of a sudden leave overnight and take a bag of money with them. In some cases they're very carefully planned," Commander Hill said, who explained that a typical scenario involves officials sending their spouses and children overseas, often using them as a conduit to shift assets offshore. With barely any assets to their name, the so-called "naked official" – as is the popular term for them in China – is then able to join their family overseas at the first whiff of trouble. "As time goes on, they start to put [their funds] into legitimate assets such as houses and property and shares and bank accounts and then the money becomes their wealth," Mr Hill, who is based in Beijing, said. "But it's never been their money to start with in the first place; it's the corrupt money flowing out of China." The sums of money believed to have been spirited out from China are staggering. The Washington-based Global Financial Integrity group, which analyses illicit financial flows, estimates that $US3 trillion flowed out of China illegally between 2005 and 2011. Since taking power in November 2012, President Xi Jinping has directed a wide-ranging anti-corruption drive aimed at regaining credibility from a public disillusioned with endemic graft in the Communist Party, while also striking fear into his opponents. The impetus for the joint operation has come from a campaign launched in July – called Operation Fox Hunt – to track down corrupt officials overseas, and to deter others from absconding.

"It's extremely difficult for public servants to go abroad now," said Lin Zhe, an anti-corruption expert at the ruling Communist Party's in-house training institution, the Central Party School. "The passports of department heads and above are withheld by the Organisation Department. When I first came to the Central Party School, there were many [international] exchanges, but this rarely happens now." The priority list agreed between the Ministry of Public Security and the AFP was culled from a broader list of "less than a hundred people", Mr Hill said, adding that the assets being pursued by China in Australia were in the "many hundreds of millions of dollars". Mr Hill said the AFP were not party to any information Chinese investigators may hold relating to Communist Party links that a suspect may have. "We only see what's on face value, this person has committed an offence," he said. "There is a human rights side; we need to make sure that we're monitoring that as well, that this is not done for political expediency where we can."

The federal government's Significant Investor Visa scheme has proven overwhelmingly popular among Chinese investors, who account for 90 per cent of applicants so far. But the difficulty in verifying the source of Chinese income had led to delays in approvals. In announcing a new "premium" investor visa last week, which allows applicants who invest $15 million to gain permanent residency after one year, the government said it would "strengthen integrity measures" to ensure the migration programme was not misused. Asked if the new visa class could lead to more corrupt officials fleeing to China, Chinese foreign ministry spokesman Hong Lei said it hoped to work with Australia to "trace fugitives and retrieve embezzlement from overseas". "The corrupt should find no safe haven in foreign countries," he said. With an extradition treaty with China yet to be ratified, Australia ranks high among the preferred destinations for Chinese economic fugitives, along with the United States and Canada. The Attorney-General can consider extradition requests for offences under the United Nations Convention against Corruption, to which Australia and China are both parties.

But immigration protection laws mean those accused have a series of claims, including applying for asylum, to avoid facing court back in China. "All criminals will always go where the weakest link is," Mr Hill said. "In the interim we're trying to develop strategies to make sure these people don't think they can just go to Australia and live happily ever after."