Israel has been gripped by a guessing game over the identity of a mysterious prisoner being held in such secrecy that even his guards do not know his name.
"Mr X" is being held for unspecified crimes and confined in total seclusion within a private wing of the maximum-security Ayalon prison.
No one knew of his existence until a story appeared on the website of Israel's leading Hebrew-language newspaper. Quoting unidentified officials within the Israeli penitentiary service, it said that Mr X was being held in the single-celled Unit 15.
He is not thought to receive any visitors and his wing is cut off from the rest of the prison by double iron doors.
Within hours, the story had vanished from the newspaper's website, allegedly after Israel's domestic intelligence service won a gagging order banning all media coverage of the case.
The disappearance of the story has, however, attracted the interests of human rights activists in Israel, who have started a campaign to force the state to unmask Mr X and disclose his crimes.
Dan Yakir, chief legal counsel for the Association for Civil Rights in Israel, said: "There is no information on whether this person has been charged, whether he has been tried or whether he has been convicted."
One Israeli security expert said that the secrecy suggested espionage rather than terrorism is likely to lie at the heart of the mystery. (© Daily Telegraph, London)