Abuja - German President Horst Koehler on Sunday called on developed nations and African countries to fight the illegal trade in raw materials.

Illegal trade in oil, timber or diamonds had to be classed as criminal and prosecuted, Koehler said at the close of the fourth Africa Forum in the Nigerian capital Abuja.

Curbing illegal trade in raw materials did not necessarily depend on the stability in Africa.

The German president also stressed that as yet unexplained issues of raw material exploration were also behind the conflict in the east of the Democratic Republic of Congo.

Koehler began a state visit to Nigeria on Monday and over the weekend participated in the Africa Forum, an initiative of his that brings together African and European business leaders. (dpa)