Video streaming start-up Quibi was accused of infringing on a patent for a key feature by video specialist Eko, weeks before the heavily-backed app’s scheduled launch, The Wall Street Journal (WSJ) reported.

At the heart of the dispute is Quibi’s turnstyle feature, a focal point at the app’s unveiling which allows videos to seamlessly move from horizontal to vertical viewing and vice versa.

Eko said it invented and patented this technology, demanding in a legal notice Quibi stops using it or licence it. The company alleges Quibi employees had access to its patent through previous roles at Snap.

In a statement to WSJ, Quibi denied Eko’s accusation, stating it had “no merit” and the turnstyle feature was developed internally by engineers with its own patent.

Switching from vertical to horizontal videos in real time isn’t a trade secret or covered by Eko’s patent, it added, explaining the feature was in development before employees moved from Snap to Quibi.

Los Angeles Times reported Quibi filed a court order to establish it did not steal Eko’s technology.

Quibi was formed by former Walt Disney Studios chairman Jeffrey Katzenberg and former HP chief Meg Whitman, who took the mantle of CEO. It is scheduled to launch on 6 April.

The mobile-only video streaming app is expected to challenge apps from providers including Netflix and Amazon Prime, with series starring Hollywood actors in exclusive shows.

Quibi is backed by heavyweights including The Walt Disney Company, JP Morgan, Liberty Global and Viacom, raising around $1.4 billion in funding.