Conille handed in a two-sentence letter of resignation, according to a government official who spoke on condition of anonymity because he had not yet been authorized to publicly release the information. No successor has been announced.

Conille, a physician who previously served as an aide to Bill Clinton in the former U.S. president's role as U.N. envoy to Haiti, enjoyed support among foreign officials and non-governmental organizations. But Haiti is sharply divided politically, and he was a target of occasional criticism in the opposition-controlled legislature.

Conille was ratified by the Haitian parliament in October after Martelly's two previous picks for the post failed to win support from lawmakers.

The delay in appointing someone to run the day-to-day affairs of the government slowed the appointment of lower-ranking officials and delayed efforts to rebuild the capital and surrounding area from a devastating January 2010 earthquake.

His resignation may have been prompted in part by a dispute among government officials over whether any of them have dual nationality, which the nation's constitution prohibits for senior government officials. Many officials in Haiti and elsewhere in the Caribbean spend considerable time overseas.

A commission of lawmakers has been investigating allegations that Martelly administration officials may have citizenship in the U.S. or elsewhere. Conille and other officials have turned over their passports and other documents to the commission but the findings of the investigation have not been announced.

Conille told The Associated Press after a news conference last week that he and Martelly were on good terms despite rumors to the contrary.

"I have a good working relationship with the president," he said. "Haiti is a big country of rumors. I think we have a very frank and honest relationship where we discuss things. I think a lot of people sometimes have a vested interest in creating a distance between all members of government so you hear that we have problems. ... I would basically think that it's mostly rumors."