The nation's largest advertisers are seeking solutions, technical and otherwise, to combat a new threat to the Internet, a growing movement to block their ads.

Dan Jaffe, the top lobbyist for the Association of National Advertisers, said it's a delicate situation that calls for a carefully thought out solution. That isn't within reach yet – even as ad blocking has erupted as a major problem.

Up to now, publishers have been the most worried about tools that strip their sites of ads, but among marketers, "concerns are growing," Mr. Jaffe said.

Mr. Jaffe said advertisers are thinking about fighting back against blocking software with rival technology that "blocks the blockers and gets around the blockers."

Some media companies have already tried this: CBS.com has prevented blockers from eliminating ads when streaming episodes of their shows.

But there could be a downside if advertisers adopt this tactic.

"We don't want to anger consumers," Mr. Jaffe said. "Everybody needs to move carefully."

To Mr. Jaffe, dislike of advertising isn't the reason people, especially millennials, are installing ad blockers on their devices.

Long initial page-load time and concerns about privacy are also driving and ad-blocking rage. These issues could be addressed, he said.

Advertisers cite a study conducted by Pagefair, a company that helps publishers defeat ad blockers, that says nearly $22 billion has been lost through anti-advertising technology.

Mr. Jaffe says the ad blocking movement has the potential to "threaten the economic viability of the media" and push more and more content behind firewalls. The world could become split into information-haves and information-have nots who can't afford to pay or are unwilling to pay for the information and entertainment that's now free, thanks to advertising, he said.

"Potentially, this could change the whole economic structure of the internet," he said.