Google has not handed over sensitive data requested by German authorities, despite a deadline of 26 May.

Dr Johannes Caspar, the Information Commissioner for Hamburg, Germany, told BBC News that there was "no sign" of the requested hard disk

The firm has until midnight to hand over data harvested by its Street View cars from private wi-fi networks.

A spokesperson for Google declined to comment further, but indicated that it would say more on the matter later.

The Hamburg commissioner also expects answers to a range of questions his office posed four weeks ago.

Dr Caspar added "We know that Google always thinks it's better to hold back the answers for as long as they are able to."

Earlier this month, the search firm admitted that it had collected information people had sent over unencrypted wi-fi networks for the last three years.

Last week, Google's CEO Eric Schmidt said that there was "no, harm, no foul", in relation to the data breach.

Google said the wi-fi data collection was a "mistake" and that it had not been authorised.

The search giant's admission came in response to an official German request to audit data gathered by Google's Street View cars.

Different approaches

Google's actions are under increasing scrutiny around the world, but countries are approaching the matter differently.

In the UK, the country's Information Commissioner's Office (ICO) has ordered the firm to destroy the data which it collected in 2008.

To allow a government to investigate a privacy breach by further violating privacy is senseless Jennifer Granick, Electronic Frontier Foundation

The ICO said it took the matter "seriously" but that it would not take any further action against the company.

Its German counterpart has asked to see the data before it proceeds, and has sought answers from Google to a range of technical questions about how the data was gathered and stored.

One of them points out that a database of unencrypted wi-fi hotspots would be very useful to criminal gangs, and asks what steps Google had taken to prevent unauthorised access.

Some countries, including Germany, have said they are considering prosecuting Google, once the extent of the data breach becomes clearer.

But civil liberties group the Electronic Frontier Foundation has questioned the wisdom of passing the data to authorities.

"Calls from some quarters for Google to simply turn over the data to the U.S. or other governments are wrong-headed," said EFF Civil Liberties director Jennifer Granick in a post on the organisation's website last week.

"To allow a government to investigate a privacy breach by further violating privacy is senseless."

Google has said that it is in discussions with data protection authorities in all affected countries about what to do with the data.