Israeli ex-nuclear technician Mordechai Vanunu has been released on bail after being arrested on his way back from a visit to the West Bank.
Mordechai Vanunu says he has averted a nuclear holocaust in the region
Police held him at a checkpoint north of Jerusalem as he was returning by bus from the West Bank on Friday.
Under the conditions for his release from prison in 2004, he is not allowed to visit the Palestinian territories.
He was jailed in 1986 for 18 years after discussing his work at the Dimona nuclear reactor with a UK newspaper.
Asked what he had done to prompt the arrest, he said: "Nothing. They just want to arrest me again. They don't want me to enjoy freedom."
Mr Vanunu served most of his jail term in solitary confinement.
He was released in April 2004 under strict conditions.
Mr Vanunu has not been allowed to have a passport, is forbidden to approach ports and airports, and is banned from talking to foreigners without permission.
Israel insists Mr Vanunu - who has converted to Christianity - still poses a security threat.
In March, he was charged with violating the terms of his release from jail by giving interviews to the foreign media.
Mr Vanunu says his action in revealing Israel's nuclear secrets aimed to avert a nuclear holocaust in the region.
Many Israelis view him as a traitor.