Yemen was ranked one of the world's most corrupt countries, coming in fourth among Arab countries and 146th out of 178 world countries in Transparency International's Corruption Perceptions Index 2010.
The index released in Berlin said the countries suffering from political and security instability such as Iraq and Yemen ranked low with respect to transparency and fighting corruption.
Most corrupt countries face challenges including the lack of effective and transparent institutions and suitable mechanisms of accountability, it said, adding that the conflicts and instability in the Middle East and North Africa are hampering anti-corruption efforts.
Other Arab countries which ranked at the bottom of the list included Somalia, the world's most corrupt country 178th, Iraq 175th and Sudan 172nd.