South Korea dropped one notch in an international corruption awareness ranking to 46th place among 177 nations in 2013, a global anti-corruption watchdog said in its annual report Tuesday.

According to the 2013 Corruption Perceptions Index (CPI) issued by the Berlin-based non-governmental agency Transparency International (TI), South Korea scored 55 out of 100.

The index shows qualitative assessments of a country's level of corruption in the administrative and public sectors, offering a yearly snapshot of the relative degree of corruption by ranking countries from all over the globe. It uses data taken from opinion surveys of experts from each country and global businessmen and analysts.

After taking 39th in 2010, the country's CPI has fallen seven notches in three years, the report said.

"The consecutive fall is not unrelated to a series of corruption linked to power witnessed in our society in the last few years," said Kim Geo-sung, the head of Transparency International Korea, the local chapter of TI. Kim referred to a high-profile corruption scandal involving the state-run operator of nuclear power plants that led to the shutdown of several reactors.

Among the 34 member countries of the Organization for Economic Cooperation and Development, South Korea came in 27th, unchanged from the previous year, the report showed.

Kim suggested various countermeasures such as "establishing an independent anti-corruption organization and strengthening surveillance on corruption among high-ranking officials or the privileged class."

Noticeably, Kim asserted that the country should reform its prosecution and launch an independent investigative body to probe corruption among senior government officials.

The reputation of the country's law enforcement agency has recently been tarnished after a number of ranking government officials, including the head of the state intelligence agency, were indicted for alleged bribery.

North Korea, which joined the list in 2011, came in last place along with Somalia and Afghanistan, by scoring 9 out of 100, according to the report.

Denmark and New Zealand were tied for the top ranking as the world's least corrupt nations, by scoring 91, it said. (Yonhap News)