Mordechai Vanunu, the Israeli whistleblower, walked free from jail today 18 years after leaking his country's nuclear secrets to The Sunday Times.

Looking fit and sounding defiant, Vanunu said that he was subject to "cruel and barbaric" treatment during his time in Shikma Prison, in the coastal town of Ashkelon, because of his religion.

"I am proud of what I did," Vanunu said, before flashing victory signs and waving to cheering supporters.

"I suffered 18 years because I was a Christian. If I was Jewish, I would not have suffered." Raised as an Orthodox Jew he converted to Christianity in the mid-1980s.

Flanked by two of his brothers as he held an impromptu news conference, he added that he had no new secrets to reveal.

He also called for Israel to open up its Dimona nuclear plant to International Atomic Energy Agency inspections and rid itself of nuclear weapons. International experts believe that Israel has produced around 200 nuclear warheads.

Vanunu, who has become a hero for the anti-nuclear movement, said: "The whole Middle East is free of nuclear weapons. Israel does not need nuclear weapons," he said.

"Open Dimona for inspection. Call Mohammed el-Baradei (the IAEA director general) to inspect it."

Speaking mostly in English - he refused to answer questions in Hebrew because of his treatment by Israel - he said: "I am now ready to start my life." Vanunu said that he now wanted to study history and teach.

He said that the Mossad spy agency and the Shin Bet security services tried to rob him of his sanity by keeping him in solitary confinement for nearly 12 years. "I say to the Shabak (Shin Bet), the Mossad, you didn't succeed to break me, you didn't succeed to make me crazy."

Supporters released doves into the air ahead of his release and then showered his car with petals as he was driven away from the prison gates.

Anti-nuclear weapons activists, including Susannah York, the actress, and Mairead Corrigan Maguire, the Nobel Peace Prize laureate, were among those gathered outside the prison.