As many as 18,000 corrupt mainland officials may have fled the country with as much as 800 billion yuan in ill-gotten gains in less than two decades, according to a study released by the central bank. The money was secreted out of the country between the mid-1990s and 2008, according to the report by the People's Bank of China's anti-money-laundering monitoring and analysis centre. The document, not originally intended for public consumption, depicts the likely extent of the problem of officials and executives from state-owned enterprises absconding with embezzled funds and bribes, long the subject of speculation. In addition to assessing the extent of the lost capital, the report also detailed the perpetrators' main routes of escape, money-laundering methods and the risks they posed to the country. Hong Kong has been widely used as a springboard for corrupt officials to flee to Commonwealth countries, it said. 'A relatively large number of defectors passed through Hong Kong and made use of the SAR's status as an international aviation hub, as well as the privilege for Hong Kong people to apply for visas in Commonwealth countries upon arrival, to flee to other countries,' it said. It said lower ranking officials who took relatively small amounts of money tended to flee to nearby countries such as Thailand, Myanmar, Malaysia, Mongolia and Russia. Higher-ranking corrupt officials, with cases involving larger sums, tended to escape to developed countries in the West such as the United States, Canada, Australia and the Netherlands. Those who were unable to obtain papers to travel directly to Western countries first holed up in small countries in Africa, Latin America or Eastern Europe as a transition measure. Many officials simply carried suitcases of cash out of the mainland, or hired people to move the money out like 'ants moving houses'. But the paper also gave examples of more complicated transactions, including money transfers through intermediaries both at home and abroad, forging false contracts, and the hiding of illicit money flow under the guise of legitimate deals. Some also used credit cards to buy huge amounts of luxury goods in Hong Kong, while paying the credit card fees on the mainland, as a way of money laundering. Casinos in Macau, Russia and Southeast Asia were also commonly used for money laundering by colluding with casino operators, the report said. The 67-page report, stamped 'internal data, store carefully' on its title page and marked as a 'discussion document', was compiled in June 2008. It was only uploaded as a public document on the bank's website after it won joint first prize in the China Society for Finance and Banking's ninth annual awards for outstanding financial research reports on Monday. The report warned that the rampant corruption was jeopardising communist rule. 'It is a direct threat to the clean-politics structure of the [Communist] Party and harms the foundations of the party's power,' the report said.