Google has been sued in the United States in a proposed class action accusing the internet search company of illegally invading the privacy of millions of users by pervasively tracking their internet use through browsers set in "private" mode.
The lawsuit seeks at least US$5 billion, accusing the Alphabet Inc unit of collecting information about what people view online and where they do their browsing, despite using what Google calls Incognito mode.
Google had no immediate comment.
The complaint said Google surreptitiously collects data through Google Analytics, Google Ad Manager and other applications and website plug-ins, including smartphone apps, regardless of whether users click on Google-supported ads.
This helps the Mountain View, California-based company learn details about users' friends, hobbies, favorite foods, shopping habits, and even the "most intimate and potentially embarrassing things" they search for online, the complaint said.
Google "cannot continue to engage in the covert and unauthorised data collection from virtually every American with a computer or phone," the complaint said.
While users may view private browsing as a safe haven from watchful eyes, computer security researchers have long raised concern that Google and rivals might augment user profiles by tracking people's identities across different browsing modes, combining data from private and ordinary internet surfing.
The complaint said the proposed class likely includes "millions" of Google users who since June 1, 2016 browsed the internet in "private" mode.
It seeks damages per user of US$5,000 or three times actual damages, whichever is greater, for violations of federal wiretapping and California privacy laws.
The law firm Boies Schiller & Flexner represents Google users Chasom Brown, Maria Nguyen and William Byatt, who filed the lawsuit in federal court in San Jose, California.
The case is Brown et al v Google LLC et al, U.S. District Court, Northern District of California, No. 20-03664.
(Reporting by Jonathan Stempel in New York; Additional reporting by Paresh Dave in San Francisco; Editing by Matthew Lewis and Grant McCool)