Releasing its annual Corruption Perceptions Index (CPI) on Tuesday, the watchdog said Afghanistan had sunk for the second straight year in its ranking of 180 nations based on perceived levels of corruption in the public sector.
The report highlights the dilemma for western governments, including the United States, which are reviewing their strategies for stabilizing the country following the re-election of President Hamid Karzai in a vote plagued by fraud , Reuters reports.
It was also reported, the group's annual Corruption Perception Index measures perceived levels of public sector corruption.
As was the case last year, the 2009 survey found that countries that scored lowest all have something in common: they are fragile, unstable and scarred by war or long-standing conflicts.
The group scored 180 countries on a scale of 0 (perceived to be highly corrupt) to 10 (perceived to have low levels of corruption).
Somalia scored 1.1.
Next came Afghanistan at 1.3, Myanmar at 1.4, and Sudan and Iraq -- both at 1.5.
On the other end of the scale, New Zealand ranked highest at 9.4, followed by Denmark (9.3), Singapore and Sweden (9.2) and Switzerland (9.0).
The United States came it at 19 (7.5) and the United Kingdom was at 17 (7.7).
"When essential institutions are weak or non-existent, corruption spirals out of control and the plundering of public resources feeds insecurity and impunity," the group said, CNN reports.
In the meantime, there were some bright spots in the new report — Bangladesh, Belarus, Guatemala, Lithuania, Poland and Syria were among the countries that improved the most.
While corruption in Bangladesh is still widespread, "a caretaker government's nationwide crackdown on corruption during 2007-2008 and the instruction of institutional and legal reforms" have improved the conditions.
In Poland, the establishment of a ministerial office for anti-corruption and an increased number of investigations into corruption have improved the situation.
"No region of the world is immune to the perils of corruption," the watchdog's report said, The Associated Press reports.