Steve Jobs discusses the Google Maps application for the iPhone during the Macworld Convention and Expo. -- PHOTO: REUTERS

'We received a report that Google Maps was collecting imagery and 360 degree views, including detailed imagery, of a base in Texas,' Mr Gary Ross, spokesman for the US Northern Command, said in explaining the Pentagon's move.

The Defence Department issued a statement that said 'detailed ground level imagery' of US military installations had been placed on Google Maps.

'Images include 360 degree views of the covered area to include access control points, barriers, headquarters, facilities and community areas,' it said.

Specifically, images of the Fort Sam Houston army base in Texas were posted, it said.

Google employees had entered military bases with permission to conduct mapping and had taken panoramic images of the area with 'roof-mounted recording equipment,' it added, referring to the activity as a 'potential threat.'

'We don't have a problem with Google Earth,' Mr Ross said of another Google website that displays detailed street and relief maps, satellite images, and 360-degree views of buildings.

'The bottom line is while they are on base they collect detailed imagery of access controls, headquarters locations, security facilities and community areas, that poses an operational risk to our force protection,' Mr Ross said.

'While it is a very useful tool, there has to be a balance.'

The department directive called on base officials to prevent 360 degree photography of base areas for use on the Internet, and to deny access to vehicles with 'imaging or surveillance capabilities' that do not have the base commander's authorisation. -- AFP