MEXICO CITY — The leader of an international anti-corruption panel in Honduras has resigned, delivering a blow to the campaign against the country’s deeply rooted corruption and throwing the future of the panel into doubt.

In a letter released late Thursday, the panel’s leader, Juan Jiménez Mayor, a former Peruvian prime minister, said that his small group of prosecutors had been abandoned as they faced rising hostility from the Honduran government.

The panel is backed by the Organization of American States, but the regional body’s secretary general, Luis Almagro, who appointed Mr. Jiménez, refused to meet with him in Washington two weeks ago. Mr. Jiménez had planned to discuss the corruption cases his prosecutors were pursuing and the resistance, including threats, that was blocking their work.

“We shouldn’t be alone, and he knows it,” Mr. Jiménez wrote.

The panel’s top prosecutor, Julio Arbizu, a former anti-corruption prosecutor in Peru, and a Chilean judge, Daniel Urrutia, also resigned from the panel.