The Metropolitan Police has launched an investigation into Google's Wi-Fi snooping incident.
Google has already admitted that it "accidentally" took some personal information relating to home user Wi-Fi accounts while collecting images for its Street View service.
UK data watchdog the Information Commissioner's Office chose not to take any action, but it appears that the police are taking a tougher line.
A post on Privacy International's web site said that crime reference number 2318672/10 has been issued by the Metropolitan Police as part of an investigation into " alleged criminal interception of wireless communications content".
Privacy International, which has described the data collection as " no accident", said that it had made the complaint under the Regulation of Investigatory Powers Act and the Wireless Telegraphy Act.
"We are pleased that the police have taken up this complaint for investigation. An evidence-based approach to this complex matter is sorely needed now," said Privacy International director Simon Davies.
"We have already told police that we will co-operate fully with any inquiries. I know Google will want to do the same. We hope that this difficult process will give Google pause for thought about how it conducts itself."
The Metropolitan Police stated that initial investigations will take around 10 days to complete, but could not give a timeline for a "main investigation" because this may involve interviewing individual employees at Google UK.
A Google spokesman reiterated the company's admission that it was "a mistake for us to include code in our software that collected payload data".
"We're working with the relevant authorities to answer any questions and concerns they have. Our ultimate objective is to delete the data consistent with our legal obligations and in consultation with the appropriate authorities," he said.
Google is also being investigated in the US and elsewhere in Europe.
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