Madrid:  A judge in Spain opened an investigation into whether Google  unlawfully collected data from unsecured wireless networks while gathering photographs for Google's photo-mapping service Street View.

The judge, Raquel Fernandino, has ordered a representative from Google to appear before her in early October over a lawsuit filed by a Spanish association of Internet users. The summons was issued last month, but made public only this week.

Street View has also caused regulatory and legal problems for Google in other European countries with strict privacy laws, including Germany and Switzerland, where opponents of the Street View photo archive have been particularly outspoken. In May, a judge in Hamburg opened a criminal investigation of Google over its collection of data from unsecured Wi-Fi networks in Germany.

Google has described the collection of the data as accidental and has apologized for what it called a programming error.

A spokeswoman for Google Spain, Marisa Toro, said on Tuesday that the company planned to cooperate fully with the judge and other Spanish authorities to resolve the privacy concerns. "We are dedicating a lot of our time to finding a solution so that users can be at ease," Ms. Toro said.

Google introduced Street View in Spain three years ago, and Ms. Toro said that it had proved "very popular." Plans to expand the coverage in Spain have been delayed pending an outcome in the data collection dispute.

The Spanish association of Internet users, whose acronym is Apedanica, contends that Google violated an article in Spain's criminal code that forbids the unauthorized interception and collection of such communications data. Breaching that law can lead to prison sentences of up to four years.

The judge's investigation is the most serious threat to date in Spain for Google and its mapping service. But Street View had already raised concerns among local regulators.

In June, Artemi Rallo, director of the official Spanish data protection agency, Agencia Española de Protección de Datos, said in an interview that Google should hand over the original hard drives containing the actual Wi-Fi payload data — including e-mail text fragments and unencrypted passwords.

Under pressure from German privacy regulators, Google acknowledged in May that it had inadvertently collected 600 gigabytes of data from unsecured Wi-Fi networks around the world as it assembled its Street View archive.

The company has already agreed to destroy the data collected in Ireland, Denmark and Austria at the request of officials in those countries.

Valentín Playá, the lawyer representing the Spanish association that filed the complaint against Google, said on Tuesday that "recognizing the mistake and the excuses presented by Google are not reasons to prevent the investigation, nor a criminal condemnation, if it is judged that the actions amounted to a crime and that there has been a degree of responsibility from Google."