A Japanese doctor who survived the 1945 atomic bombing of Nagasaki has left for Norway to attend the Nobel Peace Prize events.

Tomonaga Masao was two years old when the bomb was dropped on the southwestern Japanese city in the final days of World War Two.

He has studied the effects of exposure to atomic bomb radiation since graduating university and becoming a doctor.

The 81-year-old is not a member of Nihon Hidankyo, the Japanese organization of atomic bomb survivors that was awarded this year's Nobel Peace Prize.

Nevertheless, he was invited by the Nobel Committee to attend the award ceremony on December 10 in the Norwegian capital Oslo and to take part in a forum to discuss ways to abolish nuclear weapons.

Tomonaga left Nagasaki for Oslo on Monday morning.

He is expected to give a lecture at the forum as a medical expert and take part in discussions with young people.

Tomonaga told NHK not many people understand that the effects of atomic weapons on humans last for a lifetime, and the spread of that knowledge is slow. He said he especially wants to share this with young people.