WASHINGTON -- Senior Iraqi officials have informed the United States that Baghdad has released a Hezbollah operative who has been accused by American military prosecutors of the killing of American troops, terrorism and espionage, among other crimes, American officials said Friday.
The prisoner, Ali Musa Daqduq, was released despite the entreaties of the Obama administration. In a phone call on Tuesday, Vice President Joseph R. Biden told the Iraqi prime minister, Nuri Kamal al-Maliki, that the United States believed that Mr. Daqduq should be held accountable for his actions and that Iraq should explore all legal options toward this end, an American official said.
Robert S. Beecroft, the United States ambassador in Baghdad, made a similar appeal to Mr. Maliki that day. But Mr. Maliki told Mr. Biden that Iraq had run out of legal options to hold Mr. Daqduq, who had been ordered released earlier this year by an Iraqi court.
A lawyer for Mr. Daqduq told Reuters that he had been released by that Iraqi authorities and that he was now in Beirut. American officials have received conflicting accounts from Iraqi officials on Mr. Daqduq's status and whereabouts, but aides close to Mr. Maliki told the United States that he has been set free, said the American official, who refused to be identified because the White House has yet to comment on the case.
Press officers for the American Embassy in Baghdad and the National Security Council did not respond to requests for comment.
"We are clearly disappointed about this," said a State Department official, who asked not to be identified. "Iraqis did pursue a legal case on him and said that the evidence was not there. We do have to respect the authority of the Iraqi judiciary."
The case is noteworthy not only because of the allegations against Mr. Daqduq but also because it is regarded by Middle East experts as a test of whether the United States or Iran has more influence in Iraq. Hezbollah, a Shiite militant organization in Lebanon, is backed by Iran, a Shiite state. Iraq's government is also dominated by Shiites.
In Washington, conservative lawmakers deplored the decision to release Mr. Daqduq. Senator John McCain, the conservative Arizona Republican, called it an "outrage," and said the United States should protest in the strongest terms.
Mr. Daqduq, who was captured by British forces in Basra in March 2007, was the last detainee to be handed over to the Iraqis by the United States as American troops withdrew in December 2011.
American military officials have accused him of working with the Quds Force -- an Iranian paramilitary unit that supports militant movements abroad -- to train Shiite militias in Iraq during the war. One of the most serious allegations stems from his suspected role in helping to organize a January 2007 raid in Karbala that led to the deaths of five American soldiers.
After Mr. Daqduq was transferred to Iraqi custody, an Iraqi court ruled that there was not enough evidence to hold him. The United States sought his extradition for trial by an American military tribunal. That request was turned down.
Iraqi officials have previously said they tried to mollify the Obama administration by delaying Mr. Daqduq's release until after the presidential campaign, but American officials repeatedly insisted that they did not want him released at all.
This article originally appeared in The New York Times.