Somalia, South Sudan, North Korea and Syria are perceived to be the most corrupt countries in the world, according to Transparency International's latest annual review that draws on a mix of business and government sources for its rankings.

Somalia has held the undesirable title as the world's most corrupt country for the past ten years, with a score of 10 on the Corruption Perceptions Index 2016, which ranks countries' public sector from zero to 100.

Countries with a lower score are deemed to be more corrupt, and are generally characterized by impunity for corruption, poor governance and weak institutions, the report said.

Second from the bottom is South Sudan, a relatively new country which only gained its independence from Sudan six years ago, with a score of 11. The third most corrupt country is North Korea, followed by Syria, a war-torn country which is presently seeing a massive outflow of refugees.

Countries in the Middle East suffered the worst declines on the corruption index, led by Qatar which fell 10 scores from the previous year due to scandals such as FIFA's decision to host the World Cup 2022 in Qatar amid reports of migrant workers abuse, Transparency International said.