WASHINGTON — The Obama administration says it’s investigating software companies that make cell phone apps to determine whether they are violating the privacy rights of children by quietly collecting personal information from their phones, then sharing it with advertisers and data brokers.

Such spying apps downloaded to mobile devices can capture a child’s physical location, phone numbers of their friends and more.

In its announcement today, the Federal Trade Commission did not specify which companies it is investigating. It described the marketplace for mobile applications as a digital danger zone.

The agency examined 400 applications designed for children randomly selected from online stores operated by Apple and Google.

Most failed to inform parents about data that it could gather and who could access it. Other apps contained advertising and links to social media.