HAMBURG, Germany The United Nations has accused German chemicals and pharmaceuticals giant Bayer of stoking the war in the Democratic Republic of Congo with purchases of the mineral ore columbite-tantalite, or coltan, AFP quoted the weekly magazine *** Stern *** as reporting in its latest edition.

A report commissioned by UN Secretary General Kofi Annan, published at the end of April, said the conflict in Congo centered "primarily on access to, control of and trade in five mineral resources," including coltan, the magazine said.

Coltan is a precious hardening agent for metal used by high tech companies in the manufacture of products ranging from nuclear reactors to mobile telephones.

The UN report named Bayer's unit, HC Starck, as one of the main purchasers of coltan, meaning that it was one of the main trading companies which were helping to fuel the conflict, *** Stern ** said in an article to be published on Thursday but released in advance.

In a statement issued in response to the article, Bayer denied that HC Starck purchased any illegally-mined substances.

HC Starck's suppliers were "renowned and respectable trading partners who did not purchase illegally mined coltan," Bayer said.

Furthermore, *** Stern *** did not explain that the report had since been rejected by the UN Security Council owing to serious shortcomings, Bayer added.

For moral and ethical reasons, neither Bayer nor HC Starck would accept materials gained illegally or through damaging the environment, the German company insisted.