"To all of those who are calling me a traitor, I am proud and happy that I did what I did," a defiant Vanunu told reporters as he left southern Israel's Shikma prison as a free man shortly after 11:00 am (0800 GMT).

The one-time technician at the Dimona nuclear plant in southern Israel was abducted by secret service agents in Italy, smuggled back to Israel and then jailed in 1986 after leaking details of the plant to Britain's Sunday Times newspaper.

Vanunu said his treatment had been "cruel and barbaric" but insisted he did "not have any more secrets" to reveal.

Hundreds of foreign supporters of Vanunu gathered outside the prison to give him a hero's welcome although he is still widely perceived as a traitor by the Israeli public.

The 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.

Opponents however carried banners with slogans such as: "Death to the spy, Death to Vanunu."

Vanunu, 49, will now be subject to a series of sweeping restrictions, including a ban on travelling abroad or associating with foreigners without prior approval from the Israeli authorities.

However he said in an impromptu press conference outside the prison that he wanted to travel to both the United States and Britain.

Vanunu, who has become a cause celebre for the anti-nuclear movement, said Israel should rid itself of nuclear weapons and open up the nuclear plant to inspection by the UN atomic watchdog, the International Atomic Energy Agency (IAEA).

"The whole Middle East is free of nuclear weapons. Israel does not need nuclear weapons," he said.

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

Israeli authorities have justified the restrictions on Vanunu by warning he still has more secrets to reveal.

The Jewish state has never formally acknowledged that it possesses nuclear weapons but international experts widely believe it has produced around 200 nuclear warheads.

After his release, Vanunu was then driven to east Jerusalem where he attended a special prayer service at the Anglican church's St George Cathedral.

Vanunu's devoutly religious Jewish parents have disowned him after his conversion to Christianity.

He did not speak to reporters but the Anglican bishop of Jerusalem, the Right Reverend Riah Abu El-Assal, said prayers would be said "for Mr Vanunu, his family and friends in the hope that he can live a normal life from now on."

"He is an Anglican Christian and expressed his desire to offer thanks to God for his release from prison as his first act as a free man," the bishop added.

Ahead of his release, the director of Shikma prison said confidential information about Dimona had been found in Vanunu's cell.

"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.

Migdad said Vanunu appeared to be "very bitter", adding he did not believe that the whistleblower would "respect the restrictions which have been imposed" on him after his release.

Justice Minister Tommy Lapid justified the restrictions by saying Vanunu had "promised to do as much harm to Israel as he can."

"He is a born traitor who ... has betrayed Israel, atomic secrets, does everything that the radical left dreams about," Lapid told CNN.

Vanunu's brother Meir said he was "extremely worried for his safety".

"We have seen and heard all sorts of comments from the common people on the street that there is a threat to his life and the common people allow themselves to incite for this kind of action to possibly assassinate him."

The Sunday Times expressed delight at Vanunu's release but condemned restrictions.

"We are delighted that Mordechai Vanunu has been released after serving 18 years in jail," managing editor Richard Caseby told AFP.

"However, we are appalled that the Israeli government continues to impose such severe restrictions on his freedom of movement and freedom of speech."

WAR.WIRE