Twitter-owned live video streaming app Periscope has been targeted by HBO following the weekend's premiere of Game of Thrones series five.
Periscope allows users to stream directly form their smartphone camera, and many users used it as an opportunity to stream the episode as it was broadcast.
The Hollywood Reporter says that HBO has issued Periscope with a takedown notice, arguing that: "In general, we feel developers should have tools which proactively prevent mass copyright infringement from occurring on their apps and not be solely reliant upon notifications."
Periscope says it has a dedicated team tasked with reviewing content and that its T&Cs allow it to pull broadcasts that are violating copyright. It is, however, also at least partly reliant on users alerting it to potential infringements.
In 2014 Game of Thrones was the most pirated TV show. Its first five episodes were leaked online at the weekend, leading to a flurry of activity among torrent sharers.
While HBO in some territories allows users to access its content via its own video on demand platform, in the UK viewers are able to watch via either the Sky Atlantic channel on satellite or via Sky's on-demand Now TV service. The latter broadcasts Sky Atlantic live and also offers the show on-demand shortly after the main broadcast begins.