Nigeria has rejected as unfair a new corruption index which says the oil-rich nation is seen as the most corrupt on the African continent.
In a statement, Nigeria's Information Ministry said the index by Berlin-based group Transparency International failed to recognize the government's efforts at fighting graft.
It accused the group of using faulty and outdated information in its annual ranking of 146 nations based on perceived corruption.
Nigerian officials also say the index focuses on governments taking bribes, but ignores western companies blamed for offering illegal payments.
The index lists Nigeria ahead of only Bangladesh and Haiti as the most corrupt nations in the world.
Transparency International says corruption is often high among other oil-producing nations as well, including Angola, Chad, Libya and Sudan.