South Korea dropped two notches in a global corruption awareness ranking to place 45th among 176 nations in 2012, an international watchdog said in its annual report on Wednesday.

According to the Corruption Perceptions Index (CPI) 2012 issued by the non-governmental agency Transparency International (TI), South Korea scored 56 out of 100.

The index, based on perceived levels of public sector corruption, is an aggregate indicator that combines different sources of information about corruption. It uses data taken from opinion surveys of experts from each country and global businessmen and analysts.

After taking 39th place in 2009 and 2010, the country's ranking has never climbed over the past four years, the report said.

"The consecutive fall of the country's CPI is not unrelated to a series of corruption linked to power, witnessed in South Korean society in the last few years," the TI said.

"The new president should suggest a new blueprint to solve the corruption," it said, adding that the next administration should reflect its anti-corruption agenda in its policies.

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

The agency suggested various countermeasures such as establishing an independent anti-corruption organization and eliminating nepotism among high-ranking officials or the privileged class.

Noticeably, the agency 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 been recently tarnished by a series of bribery and sex scandals involving incumbent prosecutors, which eventually resulted in the resignation of the chief prosecutor.

North Korea, which joined the list for the first time last year, came in last place along with Somalia and Afghanistan, according to the report.

Denmark, New Zealand and Singapore were tied for the top ranking as the world's least corrupt nations, by scoring 90, it said. (Yonhap News)