The developer of PlayerUnknown's Battlegrounds has hit out at Epic's Fortnite for "replicating" its game.

In an eyebrow-raising press release, Bluehole exec Chang Han Kim slammed Fortnite's new Battle Royale mode for its similarities to PUBG. Kim said his studio was "concerned" and - ominously - stated it would "contemplate further action".

It's a surprising position to take; despite Battlegrounds' huge popularity, it is far from the first game to offer Battle Royale-inspired gameplay. It's not even the first competitor from a major publisher - GTA Online recently launched its own take, for example.

Fornite is muscling in with the might of Epic behind it, and this week announced an aggressive launch proposition: it will be completely free to download and launch on console as soon as next week, eclipsing PUBG's own Xbox One version. It's feels like it's rattled Bluepoint - not least because Epic has mentioned PUBG while talking about its competitor.

"We've had an ongoing relationship with Epic Games throughout PUBG's development as they are the creators of [Unreal Engine], the engine we licensed for the game," Kim stated. "After listening to the growing feedback from our community and reviewing the gameplay for ourselves, we are concerned that Fortnite may be replicating the experience for which PUBG is known.

"We have also noticed that Epic Games references PUBG in the promotion of Fortnite to their community and in communications with the press. This was never discussed with us and we don't feel that it's right."

"The PUBG community has and continues to provide evidence of the many similarities as we contemplate further action."

It's unclear what further action Bluepoint plans to take.