A group of hackers claims to have stolen the script for a forthcoming Game of Thrones episode and other data in a breach at entertainment firm HBO.

The group says it has 1.5 terabytes of the company’s data and has posted episodes of Ballers and Room 104 online.

It added that more material would be released “soon”.

HBO confirmed it had experienced a “cyber incident” in a statement.

In an email published by Entertainment Weekly, the hackers appeared to offer more details in exchange for favourable coverage.

“Hi to all mankind,” they wrote. “The greatest leak of cyber space era is happening.”

They encouraged recipients to download the material and added: “Whoever spreads well, we will have an interview with him.”