Mordechai Vanunu, the Israeli whistleblower who exposed Israel's nuclear arsenal to the world and paid for it with 18 years in jail, mostly in solitary confinement, was sent back to prison today for a new three-month sentence.

Vanunu, 56, was jailed for unauthorised meetings with foreigners, including his Norwegian girlfriend. Amnesty International said he had been living under a "draconian" military order and was now considered a "prisoner of conscience".

Moroccan-born Vanunu, a former technician at Israel's secret nuclear plant near Dimona, appeared at the Jerusalem district court today, where he was led away to jail. "I survived 18 years – I could survive another six," he shouted. "Are you trying to discipline me? You cannot take my freedom of expression away ... You won't get from me in three months what you didn't get in 18 years."

In April 2007 he was convicted of meeting foreigners, including journalists and his girlfriend, and was sentenced to six months. That was reduced to three months on appeal and he was given the option of community service in West Jerusalem. Vanunu said he feared being attacked and would only do the service in Arab East Jerusalem, where he lives. The court refused and today he was jailed.

"Shame on you Israel," Vanunu said: "The stupid Shin Bet and Mossad spies are putting me back in prison after 24 years of speaking nothing but the truth. Shame on you democracy, the Knesset, synagogues and the world media. Shame on you all the Arabs that are allowing me to be put back in prison. Shame on you Senate, congress, and the chairman of the International Atomic Energy Agency for not protecting my freedom. Shame on you all the world's religions, the stupid spies, the Jews, Christians and Muslims."

"Everyone knows that Israel has nuclear weapons but no one is talking about it," he said. The world doesn't want nuclear weapons – not in Israel, not in the Middle East and not anywhere in the world."

Vanunu, a convert from Judaism to Christianity, was kidnapped in a honeytrap set by the Mossad agents in Rome in September 1986. Days earlier he had spoken to Sunday Times journalists, giving them information on Israel's secret nuclear programme. His details and pictures were enough to convince foreign experts that Israel already had a significant nuclear arsenal.

He was secretly taken to Israel by ship, tried and jailed for 18 years. He spent the first 11 years in solitary confinement.

In April 2004 he was released, but was subjected to restrictions under a military order renewed every six months. He was not allowed to leave the country or to have unauthorised meetings with foreigners or to visit foreign embassies.

Amnesty International said the restrictions were not parole, because Vanunu had already served his full term. "They arbitrarily limit his rights to freedom of movement, expression and association and are therefore in breach of international law," Amnesty said.