The drones are the latest example of the State Department’s efforts to take over functions in Iraq that the military used to perform. Some 5,000 private security contractors now protect the embassy’s 11,000-person staff, for example, and typically drive around in heavily armored military vehicles.

When embassy personnel move throughout the country, small helicopters buzz over the convoys to provide support in case of an attack. Often, two contractors armed with machine guns are tethered to the outside of the helicopters. The State Department began operating some drones in Iraq last year on a trial basis, and stepped up their use after the last American troops left Iraq in December, taking the military drones with them.

The United States, which will soon begin taking bids to manage drone operations in Iraq over the next five years, needs formal approval from the Iraqi government to use such aircraft here, Iraqi officials said. Such approval may be untenable given the political tensions between the two countries. Now that the troops are gone, Iraqi politicians often denounce the United States in an effort to rally support from their followers.

A senior American official said that negotiations were under way to obtain authorization for the current drone operations, but Ali al-Mosawi, a top adviser to Prime Minister Nuri Kamal al-Maliki; Iraq’s national security adviser, Falih al-Fayadh; and the acting minister of interior, Adnan al-Asadi, all said in interviews that they had not been consulted by the Americans.

Mr. Asadi said that he opposed the drone program: “Our sky is our sky, not the U.S.A.’s sky.”

The Pentagon and C.I.A. have been stepping up their use of armed Predator and Reaper drones to conduct strikes against militants in places like Pakistan, Yemen and Somalia. More recently, the United States has expanded drone bases in Ethiopia, the Seychelles and a secret location in the Arabian Peninsula.

The State Department drones, by contrast, carry no weapons and are meant to provide data and images of possible hazards, like public protests or roadblocks, to security personnel on the ground, American officials said. They are much smaller than armed drones, with wingspans as short as 18 inches, compared with 55 feet for the Predators.

The State Department has about two dozen drones in Iraq, but many are used only for spare parts, the officials said.

The United States Embassy in Baghdad referred all questions about the drones to the State Department in Washington.

The State Department confirmed the existence of the program, calling the devices unmanned aerial vehicles, but it declined to provide details. “The department does have a U.A.V. program,” it said in a statement without referring specifically to Iraq. “The U.A.V.’s being utilized by the State Department are not armed, nor are they capable of being armed.”

When the American military was still in Iraq, white blimps equipped with sensors hovered over many cities, providing the Americans with surveillance abilities beyond the dozens of armed and unarmed drones used by the military. But the blimps came down at the end of last year as the military completed its withdrawal. Anticipating this, the State Department began developing its own drone operations.