Over the course of two weeks during the spring of 2014, according to the documents, the officer, Maj. Burimba Feruzi, received at least $42,250 in payments from a local bank account associated with SOCO.

That is the equivalent of 30 years of salary for the army officer, according to Global Witness.

Copies of the checks made out to Major Feruzi, who is no longer with the army, list the account’s name as “SOCO EXPL ET PROD BLOC V / GOMA,” an apparent reference to Goma, the city just south of the park in Congo.

Global Witness, which advocates transparency in mining, logging and energy, said it had obtained four separate checks made out to Major Feruzi totalling $15,600. The group said it had also obtained a copy of Mr. Feruzi’s handwritten and signed receipt for another $26,650, dated April 30, 2014.

“These documents show that despite SOCO’s repeated denials, the company has paid tens of thousands of dollars to an army officer accused of bribing and intimidating those trying to stop oil exploration in one of Africa’s natural treasures,” said Nathaniel Dyer, head of the Congo team at Global Witness. “These payments may only be the tip of the iceberg.”

The group called for the British and American authorities to investigate the company’s activities in eastern Congo.