Internet giant Google is in breach of Dutch privacy laws and will have to change the way it operates, the Dutch privacy watchdog said on Thursday following a seven-month probe.

"Google's combined use of personal details since revising its privacy policy in 2012 is in breach of the Law on the Protection of Personal Information," the Dutch Data Protection Authority (CBP) said in a statement.

"Google links personal details of Internet users gleaned through different Google services without informing users and without asking their permission," said the Hague-based CBP, which advises government on privacy legislation.

It invited Google to attend a meeting to discuss its concerns.

The CBP released a 100-page report on Thursday after a seven-month investigation, saying that Google's use of "tracking cookies" without clearly informing users -- or giving them a option to refuse -- was breaking the Dutch data protection act.

"Everything you do on the Internet allows Google to compile a personal profile by placing cookies ... and without permission you are not allowed to do that," CBP chairman Jacob Kohnstamm told the NOS public broadcaster.

"You have to ask users (before using cookies) -- that's what the law says and that's what we say as well," he added.

Google is being investigated by privacy authorities in Britain, France, Germany, Italy, Netherlands and Spain, the CBP added.

Failing to heed advice on privacy laws in various countries could result in fines, Kohnstamm warned.

A Google official told NOS its privacy policy did respect European legislation, adding the company would remain in talks with the CBP to solve the issue.