North Korean leader Kim Jong-un did not adapt well to an international school in Switzerland in the 1990s and his grades were poor, a news report has said.

Kim was absent for 75 days and 105 days in his first and second year at the International School of Bern, respectively, Swiss newspaper Le Matin Dimanche reported Sunday, citing unidentified sources.

Kim sometimes came to the school only in the afternoons, the newspaper said, citing an former classmate of Kim.

Kim, who used the pseudonym Pak Un, received 3.5 out of a maximum 6 in natural science and managed to get a minimum passing grade in mathematics, culture, society and German.

He was placed in an advanced English class before being downgraded to an average level and scored a minimum passing grade, according to the newspaper.

Kim only excelled in music and technical studies by scoring 5 out of 6.

Despite his reported poor academic performance, North Korea's state propaganda media have lauded Kim as "the outstanding leader"

and "another great sun."

North Korean officials have also repeatedly pledged loyalty to Kim by describing him as "the brilliant commander" and "another peerless patriot."

Kim became the supreme commander of the 1.1 million-strong military as he took over the country following the December death of his father, Kim Jong-il. (Yonhap News)