Julian Assange has threatened to sue a former friend and collaborator who has written a book portraying the WikiLeaks founder as an "emperor" who was obsessed by power and money and who had a fondness for young women.

Daniel Domscheit-Berg, a German computer scientist who was a spokesman for the whistleblowing site until last autumn, said the legal threat showed that Assange had become "exactly the kind of person he used to hate and wanted to expose".

At a press conference in Berlin, he said: "We need to set the record straight before Assange turns into a cult, a pop phenomenon."

The 32-year-old said he had received a letter from Assange's lawyer accusing him of sabotage over revelations in his memoir, Inside WikiLeaks – My Time with Julian Assange at the World's Most Dangerous Website, which is being published in 20 countries over the next week.

[I hate it when Mom and Dad fight]