Exxon Mobil Corp. XOM -0.89% is in talks to sell its oil assets in Equatorial Guinea, the country’s oil minister said, and might be replaced there by a Russian company—among other options—as U.S. companies retreat to shale projects and Moscow strengthens its foothold in African resources. Speaking to reporters on the sidelines of an energy event Sunday, Gabriel Obiang Lima said he was in talks with Exxon about a sale of its assets in Equatorial Guinea, including its operating stake in the Zafiro field. At 90,000 barrels a day, the field makes up the bulk of Equatorial Guinea’s output.

A spokesman for Exxon said the U.S. oil company is “providing information to third parties that may have an interest in these assets, but no agreements have been reached and no buyer has been identified.” The spokesman added that a potential transaction wouldn’t affect the company’s exploration activities in Equatorial Guinea. Exxon is considering selling the stake as part of its plan to shed $25 billion of assets world-wide as it turns its focus to larger projects.

Many of these investments are in U.S. shale, which has led to an unprecedented production boom in the U.S. and a reduction in exposure in Africa and other riskier places. Exxon and Chevron Corp. are also selling stakes in fields in Nigeria, historically Africa’s biggest producer. In recent years, Marathon Oil Corp. and Occidental Petroleum Corp. have also sold their stakes in Libya.