HBO's Spanish and Nordic subsidiaries accidentally made the episode available on demand for an hour
The sixth episode of the new season of Game Of Thrones was briefly released ahead of schedule in a number of countries.
In a release unrelated to the biggest hack in HBO history, the company's Spanish and Nordic subsidiaries accidentally made next week's episode - titled Beyond The Wall - available on demand for one hour, enough time for some users to download it and leak it online.
It comes a day after four people were arrested in India, accused of using exclusive access to HBO material to steal episodes and leak them online.
These two incidents happened as HBO deals with a group of hackers who stole 1.5 terabytes of information, and have been releasing episodes of several shows gradually.
Episodes of Larry David's Curb Your Enthusiasm and the Duplass brothers' Room 104 have also been leaked by the hackers.
However, the high-profile accidental release of the new Game of Thrones episode - the second-to-last in the current season - came through more official channels.
HBO Europe said it had "learned that the upcoming episode of Game of Thrones was accidentally posted for a brief time on the HBO Nordic and HBO Espana platforms."
It added: "The error appears to have originated with a third party vendor and the episode was removed as soon as it was recognised."