The letter comes in response to recent reports that the company has been quietly collecting Wi-Fi data around the world when taking pictures of streets and houses for its mapping service.

Street View, which has already rolled out in a number of countries including Australia, displays panoramic street-level photos taken by specially equipped vans which are also equipped with Wi-Fi receivers that scan private network signals as it drives through neighbourhoods

The Street View photos are overlayed onto Google Maps and concerns that Wi-Fi data could potentially be used to match mobile devices to residential addresses has privacy campaigners on alert, and they claim Google has failed to adequately explain the purpose for which they are collecting this data in Australia.

“The question is why an organisation like Google that already knows so much about individuals, that is driving around and taking photos of every street in Australia, is collecting data that could enable it to physically map that information to a physical street and presumably a physical house,” asked Geordie Guy, vice chairman of the Electronic Frontiers Australia.

The EFA and Australian Privacy Foundation are jointly drafting a letter which will be sent to Google today.

Privacy concerns

Google has taken some heat lately about its commitment to privacy after officials from ten governments including New Zealand, Canada and France wrote a letter to chief executive Eric Schmidt to express their concern over data collection for Street View and the implementation of its Buzz social networking tool.

Google claims the Wi-Fi data is only being used to help pinpoint location of mobile devices on Google Maps and other location services much like a GPS signal, and that any details it collects about the network are not published online.

However privacy advocates are seeking details of exactly what data is being captured by the Street View cars as well as assurances that its use will not extend beyond this application.

“In terms of what they are collecting about Wi-Fi networks, there's a bajillion questions we have that aren't answered there, and we're likely to have more. Google talks about wireless routers at home but what about the printers, computers, mobile phones and other devices that might be sending out wireless information,” said Guy.

The German government was surprised last month to discover that Wi-Fi data was being collected alongside Street View photographs. According to German newspaper Der Spiegel, Germany's Data Protection Commissioner Peter Schaar was “horrified” by the revelations.

The UK Information Commissioner's Office said it was also ignorant of the practice. "At no point did Google make us aware that it would be scanning Wi-Fi too", ICO spokesman Nick Day told New Scientist magazine.

Little is publicly known about Google's collection of this data. Although the company argues the information is public and therefore not in breach of any laws, it conceded last week that it could have been better publicised.

In response to why Google had not specifically informed governments of its activities, privacy spokesman Peter Fleischer said: “Given it was unrelated to Street View, that is accessible to any WiFi-enabled device and that other companies already collect it, we did not think it was necessary. However its clear with hindsight greater transparency would have been better.”

Wi-Fi data in Australia

Google Australia yesterday confirmed it was collecting Wi-Fi data in Australia. It said the collection of such data was common place, although the EFA said it was not aware of any such projects here.

One of the companies gathering this type of data for creation of location-based services is Skyhook Wireless, which operates from the US.

Guy said: “If what Google's doing is an apples-to-apples comparison with Skyhook, and that information is already collected globally by Skyhook, why not buy it off them? Cheaper than driving a van down every street in Australia right?

“Google is in a position to make inferences about that kind of data. Skyhooks doesn't have a year's worth of search history.”

Karen Curtis, Australian privacy commissioner, who did not sign the letter from government officials to Google last month, said she had been informed of the Wi-Fi data collection by Google.

“From a privacy perspective, our preliminary enquiries have indicated that the information about Wi-Fi data that Google is collecting would not be considered personal information under the Privacy Act,” she said.

However Guy said more assurances were needed. “A MAC address on a home wireless connection or any other piece of electronics that uses Wi-Fi is a serial number, it's unique. If Google rang you up (or anyone else) and asked you to read out a serial number of your mobile phone, what would you say? I'd tell them its none of their business. If I saw them on the street with binoculars trying to read it, I'd close the curtains.”

Social network security

This is not the first time Google has been questioned over its privacy policies. The botched roll out of its Buzz social network which made the contact lists of Gmail user public to other subscribers was highlighted in last month's letter to the company from international privacy officials.

“It is unacceptable to roll out a product that unilaterally renders personal information public, with the intention of repairing problems later as they arise. Privacy cannot be sidelined in the rush to introduce new technologies to online audiences around the world.

“Unfortunately, Google Buzz is not an isolated case. Google Street View was launched in some countries without due consideration of privacy and data protection laws and cultural norms.

“We therefore call on you, like all organisations entrusted with people's personal information, to incorporate fundamental privacy principles directly into the design of new online services,” the government privacy commissioners' letter to Google said.

Google responded to that letter this week with assurances that it took personal privacy seriously.

“Respecting privacy is part of every Googler's job. We also have a team of seasoned privacy professionals, including legal, policy, security and engineering experts, to help guide the development of responsible privacy policies across Google,” it said.