Haiti, Myanmar and Iraq are perceived as the most corrupt countries in the world while Finland is seen as the cleanest, a respected global graft watchdog reported on Monday.
Transparency International (TI) said in its annual Corruption Perceptions Index covering 163 countries that some of the world's poorest nations were also the most sleaze-ridden, undermining international development efforts.
"Corruption is still a cold, hard fact of life in the 21st century," the chairwoman of the Berlin-based organisation, Huguette Labelle, told a news conference.
"The reality is that it compromises the lives of millions of people and we know, according to the World Bank, that about one trillion US dollars is lost every year to bribes around the world."
The index score relates to perceptions of the degree of corruption as seen by business people and country analysts and ranges between zero, which is highly corrupt, and 10, which is very clean.
On the 2005 list, the worst levels in perceived corruption were in Chad, Bangladesh and Turkmenistan.
TI said that corruption was shockingly rampant world-wide with almost three-quarters of the countries in the report scoring below five, including all low-income countries and all but two African states.
The worst levels of corruption were seen in Haiti, which scored just 1.8, followed by Myanmar, Iraq and Guinea, which tied at 1.9.
Sudan, the Democratic Republic of Congo, Chad, Bangladesh, Uzbekistan and Equatorial Guinea rounded out the bottom 10 countries.
Labelle said that because the index is based on subjective perceptions, the fact Iraq had plummeted in the ratings may be rooted in the bigger international profile of the country since the US-led invasion in 2003 and the huge influx of reconstruction funds.
But TI chief executive David Nussbaum said the violence and mayhem wracking the oil-rich country were clearly hobbling anti-graft and rebuilding efforts.
"Corruption in Iraq is very bad," he said.
"Because there has been conflict across the country and in this case chronic conflict, that tends to mean that the things that uphold integrity in a country are not functioning."
Wealthy democracies topped TI's list, confirming the link between anti-sleaze efforts and prosperity.
Finland, Iceland and New Zealand scored a near-perfect 9.6, followed by Denmark (9.5), Singapore (9.4), Sweden (9.2) and Switzerland (9.1).
Norway, Australia and the Netherlands also made the top 10.
TI noted that while industrialised nations scored high on this year's index, corruption scandals continued to rock many of them.
A significant worsening in perceived levels of corruption was seen in Brazil, Cuba, Israel, Jordan, Laos, Seychelles, Trinidad and Tobago, Tunisia and the United States, which dropped to joint 20th place from 17th last year, with a score of 7.3.
Algeria, Czech Republic, India, Japan, Latvia, Lebanon, Mauritius, Paraguay, Slovenia, Turkey, Turkmenistan and Uruguay showed a marked drop in graft, TI said.
The organisation noted that the index includes only those countries that feature in at least three surveys, meaning that many nations -- including some which could be among the most corrupt -- were missing from the list.
TI said many countries' weak performance could be blamed in part on "facilitators of corruption", often from the West, who help political elites launder or protect unjustly acquired wealth, including looted state assets.
"Bribe payers and bribe takers are often brought together by third parties -- the facilitators who enable the corrupt to steal the wealth of nations from their citizens," Nussbaum said.
"Without them, large-scale corruption could not happen."
TI called for a number of measures to fight such facilitation including the adoption of corruption-specific codes of conduct by professional associations, professional training to ensure honest intermediaries do not become unwitting accomplices and legal sanctions for professionals who enable corruption.
It also urged stronger scrutiny of the role of non-transparent financial centres in aiding graft.