Over 80 million apps have been downloaded which carry aggressive ads and the problem was rising, LookOut said as it unveiled on Monday the first industry guidelines on how application developers and advertisers could avoid raising consumer angst over too aggressive ads, which could hit badly the $8 billion industry.

"Aggressive ad networks are much more prevalent than malicious applications. It's the most prevalent mobile privacy issue that exists," Kevin Mahaffey, LookOut's technology chief and co-founder, told Reuters in an interview.

He declined to name the most aggressive ad networks, hoping some of them would align practices to match the new guidelines which include publishing detailed privacy policy and a clear opportunity for consumers to avoid data collection.

Some more aggressive networks collect users email addresses or phone numbers without permission, while others install icons to home screens, track users whereabouts or push ads to notification bar.

"Most ad networks are not aggressive, but there are a few pushing the limits," Mahaffey said.

(Reporting By Tarmo Virki; Editing by Marguerita Choy)

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