Android users said the company violated its own privacy policy by disclosing their names, email addresses and account locations to third parties without permission.
Still not a peep, even two months after discovering that sensitive personal information was compromised in a hack of government databanks, officials say.
A flood of attacks by suspected Chinese hackers have been aimed at grabbing personal data, industrial secrets and weapons plans from government and private computers.
Both companies are seeking bragging rights in helping scientists make new medical discoveries and market share in a business that may be worth $1 billion a year by 2018.
The tech giant has been accused of invading the privacy of users of its Google Wallet electronic payment service by sharing their personal information with outside app developers.
A new study calls Facebook's privacy and data collection policies into legal question but the social giant says the authors of the research never reached out to them.