Federal prosecutors have quietly dismissed charges against a former Senegalese government official who had been accused of conspiring with a representative of a large Chinese energy company in a bribery case.

In a one-page filing, federal prosecutors in Manhattan said on Friday that they were withdrawing charges against the former official, Cheikh Gadio, but offered no explanation for the decision. Dismissals of this sort often come with agreements not to prosecute in return for testimony.

The dismissal of the criminal complaint against Mr. Gadio, who had served as Senegal’s foreign minister, came roughly 10 months after he was arrested along with Chi Ping Patrick Ho in a high-profile foreign bribery case that could shed light on the operations of CEFC China Energy, an energy conglomerate with close ties to the Chinese government.

The authorities have said Mr. Ho met Mr. Gadio at the United Nations in 2014 and later paid him $400,000 for helping to use his influence with the president of Chad to secure oil rights for the Chinese energy company in the African country. Mr. Ho, who worked for a Hong Kong research organization that got financing from CEFC, is separately charged with paying bribes to officials in Uganda to secure similar oil deals for the energy company.