(Reuters) -- Attorney General Kamala D. Harris of California said on Wednesday she reached an agreement with six major companies to provide consumers with greater privacy disclosures.

Her agreement with the six largest companies in the mobile device market - Amazon, Apple, Google , Microsoft, Research In Motion, and Hewlett-Packard - bound the companies, as well as developers on their popular platforms, to disclose how they use private user data before an app may be downloaded, Harris said.

Such disclosures are required under California's 2004 Online Privacy Protection Act. But few mobile developers have paid attention to the law in recent years because of confusion over whether it applied to mobile apps, Harris said.

Currently, the 22 of the 30 most downloaded apps do not have privacy notices, Harris said.

"Most mobile apps make no effort to inform users about how personal information is used," Harris said. "The consumer should be informed of what they are giving up."

Harris said that she will reconvene the six companies in six months to assess compliance among their mobile developers.

She raised the possibility of litigation under California's unfair competition and false advertising laws if developers continue to publish apps without privacy notices.

"We can sue and we will sue," Harris said.

(Reporting By Gerry Shih; editing by Carol Bishopric)