Argor-Heraeus, which is privately-owned, is "firmly" denying the accusations and noted that previous investigations by Swiss authorities had already cleared it of all allegations, which were first aired in a report by a panel of U.N. experts on Congo in 2005.
However, the TRIAL group said "the refinery knew or should have assumed that the gold resulted from pillage, a war crime." It also said the refiner helped to finance an unlawful armed group in a brutal conflict, which under Swiss law is a crime for "aggravated laundering."
At Monday's news conference, Kathi Lynn Austin, executive director of the Conflict Awareness Project, outlined how TRIAL based its complaint on research into "rebels supported by the gold pipeline" that she began when she worked as a U.N. investigator in the Congo nearly a decade ago.
Congo suffered back-to-back civil wars starting in 1996 in the aftermath of the Rwanda genocide that drew in the armies of other African nations in a scramble for the country's vast mineral reserves of diamonds, gold, copper, cobalt and tungsten.
Some 5 million people died before the second war ended in 2003. But much of the fighting and lawlessness has continued in the competition for minerals coming out of volatile eastern Congo, including the gold mines that soldiers and armed group leaders use to gain guns and power.
The 2005 report that Austin worked on mentions the company in connection with the sale of more than $1 million in gold by armed group leaders in eastern Congo. Another report by the U.N. experts on Congo earlier this year says gold is the commodity of choice for armed groups in eastern Congo who tend to export it through Uganda using traders that don't ask questions.
But Argor-Heraeus said in response to TRIAL's complaint that in 2005 it took the "precautionary measure" of cutting ties with a British company that sent it gold shipments and decided not to accept any more materials from Uganda.
The company, which is part of an initiative by private companies and the Swiss government to increase transparency in the gold business, also said it would cooperate with authorities on the probe.