The FBI is investigating amid fears hackers could release a host of television shows ahead of time after they claimed to have already put episodes from the upcoming season of Netflix's hit series Orange Is The New Black on to the internet.
A hacking group calling itself The Dark Overlord announced the move on Twitter with a link to an illegal file-sharing service where 10 purported episodes from the popular prison series' fifth season were available for download. The hackers said there were three more episodes in the series it had not been able to obtain.
The authenticity of the uploaded files was not confirmed and Netflix declined to comment in detail. New episodes of Orange Is The New Black were scheduled for official release on the streaming service on June 9.
Netflix has said that a small production company working with several major TV studios suffered a breach, and described it as an "active situation" that was being investigated by the FBI.
The Dark Overlord had been demanding that Netflix pay an unspecified ransom in exchange for not releasing the purported episodes.
In a statement the hackers said Netflix had remained "unresponsive" to the ransom request.
They said: "It didn't have to be this way Netflix. You're going to lose a lot more money in all of this than what our modest offer was."
The Dark Overlord claims to have stolen more series from Netflix and other studios, including ABC, National Geographic and Fox, and has threatened to release them unless "modest" ransoms are paid.
Rumours of a massive online leak of television episodes and Hollywood films have been circulating online for months.
According to reports the hackers could have access to about three dozen other television programmes and films.
They gave a list of shows they claimed to have stolen from a company doing post-production audio work in Los Angeles.
The list included NBC’s Celebrity Apprentice, CBS’s NCIS Los Angeles, Fox’s New Girl, and IFC’s Portlandia.
It was not possible to confirm the claims and none of the television networks involved have commented.
In a statement Netflix said: "We are aware of the situation. A production vendor used by several major TV studios had its security compromised and the appropriate law enforcement authorities are involved."
The Dark Overlord hackers had said in February that it did not intend to release the Orange Is The New Black episodes they claimed to be in possession of.
It was not clear what triggered the decision to demand a ransom and then release the episodes.
But the claimed Netflix release appeared to be an attempt to convince other networks to pay ransom demands.
In an online statement the hackers said: "And to the others: there's still time to save yourselves. Our offers are still on the table - for now."
Netflix has been counting on Orange Is The New Black to help it add 3.2 million subscribers from April through June, substantially higher than the company's average gain of 1.8 million subscribers in the same period over the past five years.
In a recent call with investors Netflix chief executive Reed Hastings called Orange Is The New Black one of the streaming service's "most popular and most acclaimed" programmes.