Transparency International's Corruption Perception Index of 2013 has listed Australia as among the 'big decliners' from 85 in 2012 to 81 in 2013 (on a scale from 0 perceived "highly corrupt" to 100 perceived "very clean.")

Transparency International Australia's Executive Director Michael Ahrens said the four-point drop of Australia was uncommon. He told SBS that Australia's decline may be attributed to the prosecution of Securency and Note Printing Australia executives, findings of ICAC in relation to Eddie Obeid and corruption in the New South Wales state government.

Ahrens is expected that Australia will continue its decline for the coming years because of impending corruption allegations still lodged against Australian officials at present.

The International's Corruption Perception's Index of 2013 had foreign investors as critics and the result will surely impact Australia's international image.

"Big mining countries have a look at these indexes every time they look at a new phase of development," Ahrens said.

In as much as Australia was still ranked 9th as the "cleanest" country in the world and 3rd in the Asia-Pacific region, the country is already suffering negative publicity as proven by the index.

"I guess we can account for that in the negative publicity that has come out in relation to local corruption but also the activities of a few companies in the region," he added.

"The fact is that there are a very large number of countries that rank badly in the region. That means that as we prepare to play a specific role in the 'Asian Century' ... with up to 70% of countries in the Asia-Pacific region having public sectors that are perceived to pose a serious corruption risk, there is going to be a significant danger to Australian companies unless they get much better equipped to handle it," he noted.

Transparency International's Corruption Perception's Index of 2013 served as a wake-up call against abuse of power, secret dealings and bribery continue to ravage societies around the world.

"The Corruption Perceptions Index 2013 demonstrates that all countries still face the threat of corruption at all levels of government, from the issuing of local permits to the enforcement of laws and regulations," Huguette Labelle, chair of Transparency International, said.

Denmark and New Zealand tie for first place with a score of 91.

Afghanistan, North Korea and Somalia are 2013's worst countries, scoring just 8 points each.

"The top performers clearly reveal how transparency supports accountability and can stop corruption. Still, the better performers face issues like state capture, campaign finance and the oversight of big public contracts which remain major corruption risks," explained Mr Labelle.

The Corruption Perceptions Index is based on the experts' opinions of public sector corruption. Countries' scores can be helped by strong access to information systems and rules governing the behavior of those in public positions, while a lack of accountability across the public sector coupled with ineffective public institutions hurts these perceptions.