The watchdog group found that some countries that were especially hard hit by the fallout of the global financial crisis became more corrupt during the last year. Among those were Greece and Italy, but also the United States, which declined to 22nd place, compared with 19th place last year.
Of the 178 countries surveyed, nearly three quarters fell below an index score of five on a scale where zero is the most corrupt and 10 is the least. Transparency International's corruption index draws on 13 different surveys of businesspeople and governance experts conducted between January 2009 and September 2010.
The Berlin-based watchdog group said the overall results show that greater efforts must go into strengthening governance across the globe.
"Allowing corruption to continue is unacceptable — too many poor and vulnerable people continue to suffer its consequences around the world," said Hugutte Labelle, the director of Transparency International.
"We need to see more enforcement of existing rules and laws," she said. "There should be nowhere to hide for the corrupt or their money."
Peter von Blomberg, the deputy director of Transparency International, said that a recent verdict by a U.S. federal court that allows companies to donate an unlimited amount of money to support parties made the group believe that "this strengthens the impression that one can buy political decisions with money."