The southeast Asian nation, which is highly reliant on foreign investment, dropped to a rank of 83 last year in the index of 180 countries from 77 in 2022, and its score fell to 41 from 42, according to a 0-100 scale where 0 means highly corrupt.

The index ranks countries by their perceived levels of public-sector corruption according to experts and businesspeople.

Vietnam's lower score coincided with a major crackdown on corruption last year which led to arrests and jail terms for deputy ministers, investigations of hundreds of officials and the dismissal of the then President Nguyen Xuan Phuc.

The "blazing furnace" anti-graft campaign, which is still in full swing, has intensified despite its negative effects on the economy as officials have often delayed investment decisions for fear of legal consequences amid sprawling investigations.

Vietnam's poorer showing in the index follows improvements in the previous two years, but still leaves the country in a better position than many of its regional peers, with Indonesia, the Philippines and Thailand considered more corrupt.

(Reporting by Francesco Guarascio @fraguarascio; Editing by Alexandra Hudson)