Google is now explicitly banning ad blockers that prevent ads from being served in other apps from the Google Play Store, David Ruddock at Android Police reports.

Since 2013, the company has prevented ad blocking apps from entering the Play Store, under section 4.4 of the Google Play Developer Distribution Agreement, which stated that apps should not "interfere with" or "disrupt" other apps.

However, an update to the Google Play Store Developer Policy Center on Wednesday makes that ad blocker ban far more clear.Google outlines "common violations" of its policy, which under the "device and network abuse section" includes:

"Apps that block or interfere with another app displaying ads."

This update doesn't appear to be a change in policy. It looks like Google is just trying to make it more obvious where ad blocking apps stand: They can't stop other apps from showing ads. We have contacted Google to clarify this position, but the company was not immediately available to comment.

It's a confusing territory, not least because Google still allows ad blocking browsers in the app store. These apps don't interfere with other apps, but they still prevent the display of ads, squeezing publishers' - and, indeed, Google's - revenues.

As Android Police's Ruddock writes:So, Google doesn't allow ad blockers, but apps that block ads inside themselves - like a browser - seem to be OK? The wording of Google's example in the new policy about blocking ads would seem to provide support to that position. "Apps that block or interfere with another app displaying ads." Why not just say "apps that block or interfere with the display of ads?" And I think therein lies Google's dirty little secret: ad blocking is OK ... as long as it only occurs inside your own app. Google knows that ad-blocking browsers are popular enough that not having them on Android could hurt the platform.

This tweet from ad blocking company Shine's chief marketing officer Roi Carthy also outlines the confusion around why Google would ban ad blockers in one part of its ecosystem, but not another.

1. Oh, Google.



2. Be consistent: Ban ad blockers on Chrome Store as well



3. Ad Blocking in UK up from 18% to 22% https://t.co/uZ7CWutqBE - Roi Carthy (@Roi) March 2, 2016

The confusion is compounded because Google makes money from ads both on the mobile web and through mobile apps, with the Google Display Network and AdMob respectively, so it seems odd that it would effectively ban mobile app ad blocking, but not ad blocking on the mobile web.

Presumably Google is underlining its hard line on mobile app ad blocking because it wants to protect its developer ecosystem. Google wants developers to have no barriers to monetizing their apps because they are the lifeblood of the Android platform. As mentioned earlier, we have contacted Google for clarification.

Last year, Google's then-CEO Larry Page (who is now CEO of Google's parent company Alphabet) was asked about the threat of ad blocking. He responded:

Yeah, we've been dealing with ad blocking for a long time. There's been a number of different products to do that.Part of it is the industry needs to do better at producing ads that are less annoying and that are quicker to load, and all those things. And I think we need to do a better job of that as an industry.

We've been trying to pioneer that. I think search ads are very good in that sense, and, in fact, a lot of places where ads can [be] block[ed], search ads do not get blocked because they are really useful. So I think that's a really good example of what we're trying to do.

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But I don't think there's been any major change in that dynamic in the last year or anything like that.