Twitter saw its Vine video sharing service for iPhone and iPod touch flooded with pornographic images and has now changed the app's age requirements.

The app, which allows users to post and share short videos of up to six seconds, has received lots of criticism almost immediately after it launched last month, as the service's feature to delete videos after six seconds has turned into a sexting app.

Not only did the app draw criticism and raise concerns very soon after launch, but it took controversy to a whole new level when a pornographic video made Vine's "Editor's Pick," further fueling concerns that the service is actually a porn venue.

After receiving numerous complaints of freely available pornography, Twitter has now decided to impose a more adequate age restriction, and now requires users to confirm they are at least 17 before they can download the app. The previous age restriction was 12+, but obviously that turned out to be less-than-appropriate.

The update to the Vine app on iTunes now notes that users under age 17 cannot download the app, and warns that the service packs "frequent/intense sexual content or nudity."

Vine had already started to censor porn-related searches on the app after the firestorm of controversy and criticism, but raising the age restriction was an overdue step for the app to continue to be available on iTunes.

Apple already removed photo-sharing app 500px from its App Store after finding that users were posting adult content. That app later returned to the App Store with a 17+ rating to avoid the same issues, and Vine seems to follow the same trajectory. Even Tumblr has raised its age restriction following similar concerns from the Cupertino giant, and Tumblr is mostly about blogging, not adult content.

In addition to setting the new age restriction to 17+, Vine's latest 1.0.5 update also adds new functionality which now allows users to report or block a profile if they find inappropriate content. The update also brings some "miscellaneous bug fixes," including issues that prompted a black screen and caused uploads to fail after creating a video on certain devices.