Switzerland has opened a corruption investigation into mining and commodity giant Glencore and its activities in the Democratic Republic of the Congo.

Glencore, one of the world’s largest companies, announced earlier this month that Switzerland’s Office of the Attorney General is probing the company’s “failure to have the organizational measures in place to prevent alleged corruption” in the DRC.

Swiss-based Glencore said it would cooperate with the investigation. It is reportedly the biggest western company operating in the DRC, Africa’s largest copper producer and a source of much of the world’s cobalt.

The Swiss investigation comes on top of probes in the United States and the United Kingdom into compliance with the Foreign Corrupt Practices Act and money-laundering and other laws.

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Glencore, which owns and controls mines as well as oil and grain subsidiaries around the world, has long faced — and denied – accusations of financial wrongdoing, pollution and labor violations.

In 2017, the International Consortium of Investigative Journalists and media partners revealed as part of the Paradise Papers investigation that Glencore provided a $45 million loan to a company controlled by a businessman then negotiating a mining deal with DRC officials. The businessman, Israeli millionaire Daniel Gertler, nurtured close ties to Congolese politicians.

This floor plan – a document form the Paradise Papers – shows where the Glencore room was in the Appleby’s Bermuda office.

Following the publication of the Paradise Papers, the U.S. Treasury sanctioned Gertler for having “amassed his fortune through hundreds of millions of dollars’ worth of opaque and corrupt mining and oil deals.” Gertler denies wrongdoing.

Federal prosecutors launched the probe into Glencore following a complaint submitted in December 2017 by nonprofit Public Eye, according to ICIJ media partner Tamedia. In its complaint, Public Eye said that ICIJ’s Paradise Papers investigation “brought new explosive elements of this high-risk partnership to light.”