The Berlin-based Transparency International has issued its annual corruption perception index, which shows little change from last year.
Transparency International says two-thirds of the 159 nations surveyed have a bad record on corruption. The countries identified as most corrupt tend to be the poorest. Bangladesh, Chad and Turkmenistan rank at the bottom. But David Nussbaum, the chief executive of Transparency International, says some developing countries have registered significant improvements.
"There are some of the poorer countries in the world that have been able to improve their scores even though they were quite low. For example, Bulgaria, Colombia and Estonia have all improved over the last few years," Mr. Nussbaum says.
Mr. Nussbaum spoke on Bloomberg television. There is, he says, a direct link between corruption and poverty.
"One of the links is that corruption tends to cause poverty and make poverty worse than it would otherwise be. And that is devastating for the lives of ordinary people who find, for example, that they are having to pay bribes for services they ought to be entitled to free from their governments by way of health care or education, and so forth," Mr. Nussbaum says.
Nigeria is among the countries that showed improvement over the past year.
Countries perceived to be the least corrupt are Iceland, Finland and New Zealand.