"The euthanasia has taken place," Jacqueline Herremans, a member of Belgium's federal euthanasia commission, told AFP.

She added that the assisted death had taken place according to Belgian law.

Wim Distelmans, head of the euthanasia commission, gave no details of the minor involved beyond saying it was an exceptional case of a child with a terminal illness, the Het Nieuwsblad newspaper reported.

VRT public television said the incident involved an adolescent who was about to turn 18.

"Fortunately, there are very few children who are considered (for euthanasia) but that does not mean we should refuse them the right to a dignified death," Distelmans told the newspaper.

Since 2014, when its euthanasia legislation was amended, Belgium has been the only country in the world that allows terminally-ill children of any age to choose to end their suffering -- as long as they are conscious and capable of making rational decisions.

The Netherlands also allows mercy killings for children, but only for those aged over 12.

- 'Very controlled' -