The U.S. Defence Department 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 Defence Department bases and installations around the country late last week told officials not to allow the mapping website to take panoramic views inside the facilities.

Air Force Gen. Gene Renuart, chief of the U.S. Northern Command, said Thursday that that the decision to issue a formal ban was made after at least one Google crew requested and was permitted access to a base, identified in the message as Fort Sam Houston.

Renuart said he was concerned that allowing the 360-degree, street-level view could provide sensitive information to potential adversaries and endanger base personnel.

"[It shows]where all the guards are, it shows how the barriers go up and down, it shows how to get in and out of buildings, and I think that poses a real security risk to our military installations," he said.

Google says mapping was mistake

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

"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 a parliament building in Britain.

Renuart stressed that the military ban was not an attack against Google, but that it was more a concern about secondary effects of an otherwise good technology.

"Google was very appreciative of us letting them know that we had a concern," he said. "They understand the security implications, and they have given us no indication that they would not be helpful to us if we asked."