Apple is letting developers make ad-blocking tools for its Safari mobile web browser on iOS 9, threatening revenues for businesses that rely heavily on advertising.
One of the changes in iOS 9 – Apple's operating system for iPads and iPhone set to be released later this year – will be the ability for app makers to create "Content Blocking Safari Extensions".
The iPhone maker already has ad blockers for the desktop version of Safari, but bringing it to mobile could hit advertising revenues for publishers in particular, at a time when revenues from mobile ads are on the rise. The proposed ad-blockers won't affect advertising in apps, only in the mobile Safari internet browser.
"Blocking gives your extensions a fast and efficient way to block cookies, images, resources, pop-ups, and other content," according to documents given to app makers at Apple's Worldwide Developers Conference this week.
The move marks a bigger emphasis on privacy from the Cupertino, CA-based company. Speaking over video link at an event organized by privacy research group EPIC earlier this month, Apple CEO Tim Cook said "people have a fundamental right to privacy", which was seen as a dig at Google and Facebook's use of personal data.
Mobile is the fastest-growing advertising format and generated $42.6 billion in global revenues in 2014, according to eMarketer estimates. This is expected to increase by around 60 percent to $68.6 billion this year.
But at the same time, the number of people using adblocking software has surged. There were about 144 million active adblock users around the world last year and the number of consumers using these type of apps boomed 70 percent between June 2013 and June 2014, according to an Adobe and PageFair study.
Given that Apple users are often seen as a wealthier than those using other devices, the availability of ad-blocking apps could be damaging for the publishing industry in particular, which heavily relies on advertising.
"For the many news companies who are counting on mobile advertising for their future business model, I don't see a way that this change won't shave off a real slice of mobile advertising revenue," Joshua Benton, director of Harvard University's Nieman Journalism Lab, wrote in a blog post.
The technology giant has followed other companies in moving to block ads that users often see as annoying. Last month, a Financial Times report claimed several European mobile networks were planning to block ads for users on web pages and apps.
But not all industries will be affected. Retail companies, which often uses targeted banner ads to suggest items that users might like to purchase, won't see a big hit, according to experts.
"What I am seeing a lot of retailers I work with is that digital marketing is not very valuable in the first place," Michael Ross, co-founder of OrderDynamics, a company that helps retailers use big data, told CNBC by phone.
"The smart retailers are working on how to come up with advertising that is added value content and talking to consumers in way that will engage them."
Marketing experts said Apple's move will cause a "rethink" in the industry and force advertisers to create more relevant adverts.
"People are actually okay to get advertisements and offerings if it's in the right context and in relation to their location," Guillaume Le Mener, head of data monetization at Tektronix Communications, told CNBC.
"It is a good thing for Apple to do that and will force the industry to rethink how they push mobile advertisements."