LONDON (Reuters) - The U.S. Department of Justice is seeking documents from Glencore GLEN.L about intermediary companies that the commodities firm has worked with in the Democratic Republic of Congo, Venezuela and Nigeria, sources familiar with the matter said.

FILE PHOTO: The logo of commodities trader Glencore is pictured in front of the company's headquarters in Baar, Switzerland, November 20, 2012. REUTERS/Arnd Wiegmann/File Photo

The investigation is not directed at Glencore’s own activities or its senior executives, two sources told Reuters, giving no further detail about the type of information sought.

“The investigation focuses on intermediaries,” one source familiar with the probe said. A banker working with Glencore also said the focus was on three intermediary firms.

In mining and other extractive industries, intermediaries are firms or individuals paid a fee by producers, buyers or both for services such as brokering deals.

Glencore said on July 3 it had been subpoenaed for documents relating to its business in the three countries since 2007, sending its shares down 13 percent and leaving investors guessing about the direction of the investigation.

The Switzerland-based firm had said the subpoena related to compliance with the U.S. Foreign Corrupt Practices Act and money-laundering statutes but did not indicate the Department of Justice was focused on intermediaries or give further details.

Glencore, which said on July 11 it would cooperate with the U.S. authorities after receiving the subpoena, declined to offer additional comment for this article. The Department of Justice declined to comment.

A third source, who was familiar with the Nigerian element of the probe but not other areas, said the Department of Justice wanted Glencore to hand over documents related to associates of former Nigerian oil minister Diezani Alison-Madueke, namely the owners of Nigeria-based Atlantic Energy Holdings.

The U.S. authorities are investigating alleged bribery of the former minister and alleged money-laundering by her associates, who include Olajide Omokore and Kolawole Aluko, according to U.S. court documents seen by Reuters.

Glencore was a buyer of oil from Atlantic Energy Brass Development, a subsidiary of Atlantic Energy Holdings, which was owned by Omokore and Aluko.

Glencore declined to comment on its oil dealings with Atlantic Energy. A lawyer representing both Atlantic Energy and Omokore also declined to comment.

A lawyer for Alison-Madueke requested Reuters send questions by email, but did not respond when that email was sent.

A lawyer for Aluko could not be identified, as court documents did not name a representative and other lawyers involved in the case could not offer guidance.

Nigeria’s government referred requests for comment to the justice minister, who is also attorney general. He did not respond to requests for comment.

For Congo, the U.S. authorities were seeking documents from Glencore relating to Israeli billionaire Dan Gertler, while for Venezuela they wanted documents from Glencore relating to Miami-based trading firm Helsinge Inc, the first source and the banker said.

The sources declined to disclose any more information about the probe into these two intermediaries.

Gertler, who was a partner in Glencore’s cobalt and copper mines in Congo until 2017, could not be reached for comment. His spokesman in London declined to comment.

Congolese government spokesman Lambert Mende said Gertler had business in Congo and that any investigation into his activities had nothing to do with the government.

For Venezuela, Helsinge acted as an intermediary for Glencore’s fuel sales to state energy firm PDVSA, according to PDVSA’s internal trade documents seen by Reuters.

Helsinge did not respond to telephone or email requests for comment about the Department of Justice probe.

A spokesman for PDVSA did not immediately respond to a request for comment.