A new video-sharing app that allows users to create six-second looping videos is under scrutiny after questionable content was featured in the app.

Twitter announced the release of Vine, a mobile service that allows users capture and share short videos, last week.

Similar to Twitter’s 140-character limit, Vine forces users to be creative and concise with a six-second-or-less limit on the videos.

The app was described by TechCrunch as Twitter’s response to Instagram -- a hugely-popular photo-sharing app that was purchased by Facebook for $1 billion.

Like Instagram, Vine integrates with Twitter to embed videos directly in tweets and users can follow other Vine users.

It didn’t take long for the app to gain momentum. On Friday, a day after its release, Vine was featured in Apple’s App Store.

However, Vine was on the receiving end of some criticism on Monday after a pornographic video made it to the top of the app’s Editor’s Pick -- which is where users can browse some of the top Vine videos.

A statement by Twitter released on Monday says “human error” was behind the six-second porno being featured on the site and the video has since been removed.