WASHINGTON - An employee of a U.S. spy agency has confessed to operating a small drone that crashed on the grounds of the White House, the agency said on Tuesday, the latest in a series of incidents that raised questions about the president's security.

A spokesman for the National Geospatial Intelligence Agency (NGA) said that an off-duty employee had told the U.S. Secret Service, which guards the presidential mansion, that he had been flying the four-propellor drone when it crashed on Monday.

The NGA is a Defense Department agency whose principal job is to analyze photographs taken by spy planes and satellites.

The spokesman said that the Secret Service was investigating and at this point the man was not facing disciplinary action. It did not name the employee or explain why he was operating the device near the president's home.

A Secret Service spokesman said the device, which set off an alert and a lockdown at the White House, was used for recreational purposes and did not appear dangerous.

President Barack Obama, who was traveling abroad, said he understood the drone was of a type available at a high street chain store and the incident illustrated the need for more regulation over such new technologies.

Obama's wife, Michelle, accompanied the president on the trip. Their daughters, Sasha and Malia, and their grandmother, Michelle Robinson, stayed behind.

In an interview with CNN, Obama said he had asked the Federal Aviation Administration to examine how the United States is managing the influx of flying devices "because the drone that landed in the White House you buy in RadioShack."

The device known as a "quad copter" crashed at the White House in central Washington in the early hours of Monday without endangering anyone.

Asked by CNN if he was confident that another drone that was armed could not land at his residence in the future, Obama demurred. "This is a broader problem," he said. "I'll leave the Secret Service to talk about this particular event."

The Secret Service has come under scrutiny after several incidents involving White House security. Its director resigned in October, and an independent review concluded that it needs to build a better fence and hire more officers.