Oman dropped four ranks in the Corruption Perceptions Index 2017 reaching 68th rank globally.
The Sultanate scored 44 points last year, hitting a five-year low.
Similarly Kuwait dropped from 75 to 85, while Bahrain experienced the sharpest drop in the index since last year (from 70 to 103).
The United Arab Emirates got a better rank this year, jumping from 24 to 21 while Saudi Arabia increased from 62 to 57 and and Qatar from 31 to 29.
The report cited that the better ranks that UAE and Qatar have achieved “may be due to good and efficient management of public finances, improved public procurement and better access to public services and infrastructure,”
However, it stated that the report “does not capture the whole and varied picture of corruption”.
The worst performing Arab states in the index – Iraq, Libya, Somalia, Sudan, Syria, and Yemen – all suffer from weak public institutions, internal conflict and deep instability, according to the report.
The index, which ranks 180 countries and territories by their perceived levels of public sector corruption according to experts and business people, uses a scale of 0 to 100, where 0 is highly corrupt and 100 is very clean.
This year, the index found that more than two-thirds of countries score below 50, with an average score of 43.
This year’s Corruption Perceptions Index highlights that the majority of countries are making little or no progress in ending corruption, while further analysis shows journalists and activists in corrupt countries risking their lives every day in an effort to speak out.
This year, New Zealand and Denmark rank highest with scores of 89 and 88 respectively. Syria, South Sudan and Somalia rank lowest with scores of 14, 12 and 9 respectively. The best performing region is Western Europe with an average score of 66. The worst performing regions are Sub-Saharan Africa (average score 32) and Eastern Europe and Central Asia (average score 34).