Next week's episode of Game of Thrones has surfaced online five days ahead of its scheduled broadcast.
According to reports the sixth episode of the seventh season of the show, which is due to air next Monday, Australian time, was aired in full by the HBO channel in Spain overnight.
Reports also suggest it was available via the streaming portal HBO Nordic, which services Denmark, Finland, Iceland, Norway and Sweden.
HBO Nordic is roughly identical to HBO's other streaming portals HBO Go, which is marketed to cable television subscribers in the US, and HBO Now, which is a standalone streaming service in the style of Netflix.
All three host on-demand libraries of HBO content and, in some markets, also have first run rights to Game of Thrones, which is HBO's most valuable programming asset.
The leaked episode took some time to surface fully; initially a handful of clips filmed with mobile phones and screen grabs of key scenes from the episode surfaced.
Several hours later the first links to the full episode went into circulation, though many fans online are cautioning others away from spoiling the story at what is seen as a critical juncture.
Others mocked Spanish fans for being so slow to put a pirated copy of the episode into circulation.
The leak comes after an earlier episode of Game of Thrones, handled by a contractor to News Corp's Star India, was also leaked online.
An investigation into that case resulted in four arrests earlier on Tuesday.
It also comes in the wake of a hacking scandal, in which HBO's computer network was compromised and Game of Thrones scripts and storylines from the current season were also leaked online.
The current season, the second to last for the hit show, aired its fifth episode last Monday.
A statement issued by HBO Europe confirmed the glitch.
"We have learned that the upcoming episode of Game of Thrones was accidentally posted for a brief time on the HBO Nordic and HBO Espa??a platforms," the statement said.
"The error appears to have originated with a third party vendor and the episode was removed as soon as it was recognised."
HBO Europe's statement added the event was "not connected to the recent cyber incident at HBO in the US."