Google said Tuesday it would allow Germans to opt out of its disputed Street View navigation service ahead of its launch in the country this year but privacy watchdogs were still not happy.

The move is part of an effort to placate German authorities, who have serious concerns about the service that allows users to view online panoramic still photos at street level taken using specially equipped vehicles.

"Google will roll out Street View for the 20 biggest German cities by the end of the year," the company said in a statement, meaning Germany will join the list of 23 countries featured on Street View.

The service, launched in 2007, allows users to view street scenes on Google Maps and "walk" through cities such as New York, Paris or Hong Kong on their computers or smartphones.

But Street View has been dogged by legal problems. On Tuesday South Korean police searched Google offices on suspicion of breaching privacy laws while collecting information for the service.

The debate has been particularly heated in Germany, where authorities forced concessions from the Internet giant.

"Germany had very unique experiences with data protection during the two dictatorships," under the Nazis and the East German communists, said Internet specialist Falk Lueke of the VBVZ consumers association.

Uniquely for Germany, Google will launch a campaign Wednesday informing citizens concerned about safety or privacy how they can have pictures of their homes or businesses pixelled out before they are published.

"Renters or owners can apply to have their building made unrecognisable before the pictures are published online" from next week, the company said.

Google already blocks out people's faces and car number plates in the other countries featured on Street View and will also do so in Germany.

In April Consumer Affairs Minister Ilse Aigner and Google reached an agreement after a lengthy dispute under which the company would only provide Street View images from Germany after it had addressed privacy concerns.

Aigner, a fierce defender of privacy rights online, made headlines in June when said she would delete her Facebook profile over data protection issues.

She welcomed Google's concessions as a victory for her hardline stance.

"My demands and the public debate about Google publishing information about homes and property on the Internet have borne fruit," her ministry said in a statement.

Google's announcement failed to silence the most vocal critics, who said the opt-out policy was far too complicated.

Johannes Caspar, the commissioner for data protection and freedom of information in Hamburg, where Google's German unit is based, said he was "stunned" about the quick roll-out.

"My concerns about implementing these complex opt-out proceedings were unfortunately not respected," said Caspar, who was involved in the initial negotiations with the company,

He noted that Google was launching the campaign when many Germans are still away on their summer holidays and was limiting it to four weeks, after which photographs can only be pulled from the Web post-publication.

Lueke said the launch would be an experiment for Google and Germany.

"Many problems will only be identifiable once the software is launched," Lueke said. "For example, will faces be better pixelled out than in Britain, where you can still recognise them?"

The company noted, however, that Germans were already among its most avid users of Street View when making their travel plans abroad, with nearly one million clicks per day.

"That is the problem: no one wants to see his house on the Internet. But everybody wants to find photos of their vacation rental," Lueke said.