ASHKELON, April 21: Israeli nuclear whistleblower Mordechai Vanunu emerged defiant after 18 years in prison on Wednesday, saying he was proud of revealing secrets that exposed the Jewish state as an atomic power.

Mordechai Vanunu flashed victory signs and waved as he walked through the gates of Ashkelon's Shikma Prison, where supporters cheered him as a "peace hero" and counter-demonstrators booed him with chants of "Shut up, atomic spy".

"I am proud and happy to do what I did," the grey-haired, former nuclear technician said standing before a bank of television cameras flanked by two of his brothers. The head of the prison said confidential information about Israel's Dimona nuclear plant had been found in Mr Vanunu's cell before the release.

"The security services have searched his cell and examined his notebooks and letters that he wants to retrieve once he is freed. Anything which reveals confidential information has been seized," said Yossi Migdad.

Mr Vanunu's 1986 revelations to a British newspaper about the top-secret Dimona reactor led security analysts to conclude Israel had amassed an arsenal of 100 to 200 nuclear warheads, one of the world's largest stockpiles.

Mr Vanunu, 49, complained bitterly of "cruel and barbaric treatment" at the hands of Israel's security services, but insisted he had no more state secrets to divulge after serving his full term on a conviction for treason and espionage.

Fearing he could leak more classified information, Israel put him under close surveillance and slapped restrictions on his movements, including a one-year ban on travel abroad. Violations of these conditions could land him back in jail.

Mordechai Vanunu, a Moroccan-born immigrant, refused to answer questions in Hebrew during an impromptu news conference broadcast live on state television, saying he was protesting Israel's limits on his contacts with foreigners.

Supporters fear for his safety in Israel, where most people despise him as a traitor. "Israel doesn't need nuclear arms, especially now that all the Middle East is free of nuclear arms," Mr Vanunu said. "My message...to all the world is open the Dimona reactor for inspections."

In his first stop, Mr Vanunu, a Christian convert, prayed at the Anglican Saint George's Cathedral in occupied Jerusalem and met there an American couple who adopted him. Most of his own family has disowned him. -Reuters/AFP