WASHINGTON — Citing security risks, the Pentagon banned Google teams from making detailed street-level video maps of U.S. military bases after images of a Texas base ended up on the popular Internet site.

A message sent to all Defense Department bases and installations around the country late last week told officials not to allow the mapping Web site to take panoramic views inside the facilities. Google said taking such pictures is against its policy and that the incident was a mistake.

Air Force Gen. Gene Renuart, chief of the U.S. Northern Command, said yesterday that the decision to issue a formal ban was made after at least one Google crew requested and then was permitted access to a base, identified in the message as Fort Sam Houston. He said he was concerned that allowing the 360-degree, street-level view could provide sensitive information to potential adversaries and endanger base personnel.

Google spokesman Larry Yu said a Google crew mistakenly asked for access to a base.

"It is against our policy to request access to military bases for the purpose of capturing imagery in Street View," he said, adding that when Google was contacted, the imagery was taken off the site within about 24 hours.

Street View is a feature on Google Map pages that allows viewers to click on a location and see a panoramic view of that spot.

The issue emerged just a few days after published reports suggested that protesters used Google Earth to help plot their access to the roof of the Parliament building in London.

According to the message sent by U.S. Northern Command to military installations around the country, Google representatives requested access to Fort Sam Houston and were granted permission.

"Once given access, they took panoramic images of the area with roof-mounted recording equipment," the message said. "These images were placed on the Internet for public access." The imagery included views of entry gates, barriers, the headquarters and other facilities.

The message ordered that military bases prohibit such photography, report any vehicles that may have surveillance capabilities and report any incidents where such access was granted.