Hundreds of mobile apps for children fail to provide parents with basic information on the kinds of sensitive information the apps collect and share about their children, said a new federal report Monday.

Only 20 percent of children’s apps provided disclosures about their data collection practices, according to a staff report from the Federal Trade Commission released Monday. The apps that did offer disclosures often provided links to long, dense, technical privacy policies ‘‘filled with irrelevant information,’’ according to the report. Other apps, it said, gave misleading information about their practices.