Insurgents could be using satellite images from a popular website to mount attacks on British and American bases in Iraq, defence experts said last night.

Google Earth allows users to zoom in on almost any location in the world to such close range that cars can be recognised. The site even provides latitude and longitude co-ordinates for buildings.

Bill Sweetman, a technological warfare expert with Jane's, the military and intelligence specialist publisher, said the images could enable terrorists in Iraq to pinpoint targets inside military bases.

"Information gleaned from Google Earth can be of use to these people," he said. "They can use overhead images to get co-ordinates for a mortar attack or for a suicide bomber to try to figure out where a building is in the base so they don't get lost on their way in."

The Google Earth website, which uses free software downloaded from the internet, was launched this summer and has attracted a variety of users, from web surfers wanting to see a view of their home from space, to people searching for the hotel nearest the beach. It has also been used to help relief workers to get resources to the scenes of natural disasters such as Hurricane Katrina.

But since its launch, allied forces servicemen in Iraq have suspected that terrorists are using it, along with GPS (global positioning system) units - available in the high street for as little as £150 - to carry out attacks on their bases.

In an e-mail recently posted on the internet, a United States marine who has served in Iraq lamented how the rebels were using easily available resources. "Bad guy technology: simple yet effective," he wrote. "They use GPS units for navigation and Google Earth for overhead views of our positions."

Brian Collins, a professor of information systems at Cranfield University, said: "Coalition soldiers will have access to more up-to-date images, but websites like Google Earth give these people [insurgents] the possibility of levelling the playing field a bit. If you can locate a target on the image it will give you very accurate co-ordinates and a terrorist will know exactly where to aim a missile. If you also have a GPS then you know exactly where you are and you can sit there with your PC and look at these very high resolution satellite image and you will know where to fire your missile from and what to fire it at."

The images on the website are not live and are, on average, about 18 months old, but Prof Collins said this would not make them obsolete as an aide for terrorists. "If you were interested in vehicles, then that would be a problem but if you are looking at a fixed installation like a military base then it won't have changed that much."

The Conservative MP James Arbuthnot, who is the chairman of the House of Commons defence select committee, last night promised to look into the claims.

A spokesman for Google said it acquired the images from a number of companies and that the data was already available from these sources directly.

"We takes governmental concerns about Google Earth very seriously and welcome dialogue with governments about any concerns they may have," she added.

"Our technology is used for vital purposes such as fighting forest fires and emergency response.

"We believe that the benefits of access to the information provided by Google Earth for such valuable purposes are greater than any negatives from potential abuse."

A spokesman for the Ministry of Defence said: "Google Earth is compiled from still images that are already available from both commercial and public sources. The pictures are very dated and do not show any live activity."