North Korean leader Kim Jong-un lived in Switzerland from the age of seven, arriving two years earlier than previously thought, the Swiss paper Le Matin Dimanche reported on Sunday.

Previously Swiss media had placed his arrival in Switzerland in 1993 when he was around nine years old.

But the paper cited documents it had obtained from federal police archives at the public ministry to show he had stayed in Switzerland between late 1991 and early 2001.

The paper said it had obtained a document showing a request for accreditation of a certain Nam Chol Pak to work as a bureaucrat for North Korea's foreign ministry.

The document showed that the official arrived on November 25 1991, with his wife, two sons and a daughter.

The two boys were the two youngest sons of Kim Jong-il, who ruled North Korea from 1994 until his death in December last year.

But they used the pseudonyms Chol Pak and Hun Pak while in Switzerland, and Hun Pak was Kim's alias, the paper said.

Little is known about the boy's formative years in the country. Schools where he was reportedly enrolled have refused to discuss his time there.

According to Swiss and foreign media, he was a pupil at an international private school in Guemligen, near the Bern suburb of Muri, and later attended a public school in Liebefeld, also near Bern.

Le Matin Dimanche, quoting an unnamed former classmate, reported early this month that he scored poor grades and was often absent.

The boy's false father initially worked for North Korea's mission to the United Nations in Geneva and was later transferred to the North Korean embassy in Muri, the paper said. (AFP)