Game of Thrones Periscope broadcasts anger HBO

Daenerys Targaryen, portrayed by Emilia Clarke, appears in a scene from series four of Game of Thrones

Games of Thrones broadcaster HBO has sent "take down" notices to Periscope, the live-streaming video app owned by Twitter, after users of the app broadcast episodes of the hit show on Sunday night.

HBO also said Saturday's online leaks of four episodes had come from within a group that had received preview DVDs.

Twitter maintains that the Periscope app complies with US copyright law.

But HBO indirectly criticised the video streaming company.

"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," HBO said in a statement.

Periscope's terms and conditions make it clear that users should respect intellectual property rights, but the app currently only reacts to copyright infringement allegations rather than trying to prevent them happening in the first place, HBO believes.

The long-awaited series five of Game of Thrones aired in the US on Sunday and in Europe on Monday.

'Hundreds of millions'

Copyright infringement has been a huge issue for HBO.

Episodes of the first four series of Game of Thrones were illegally downloaded more than seven million times between 5 February and 6 April this year, according to piracy specialist Irdeto, as marketing for the new series ramped up.

This was a 45% increase on the same period last year, the company said.

But over the history of the series, illegal downloads had run into the "hundreds of millions", Ernesto Van der Sar, of the Torrentfreak news website, said.

And the first episode of the new series had been downloaded up to five million times, he said.

"In my view, Periscope is a non-issue [for Game of Thrones] because the show is already posted online at very high quality on several other services," he says.

"But mobile live streaming could be more of an issue for live sporting events like football matches."