The Jerusalem Magistrate's Court has sentenced nuclear whistleblower Mordechai Vanunu to six months in jail for violating the terms of his parole.

Vanunu, a former technician at Israel's nuclear plant near the southern town of Dimona, spent 18 years in prison for giving details of the country's atomic program to British newspaper "Sunday Times" in 1986.

Upon his release in 2004, Vanunu was banned from leaving the country and talking to foreigners without approval, because Israeli authorities claimed he could still divulge classified information.

Some two months ago, Vanunu was convicted of 14 parole violations including contacts with journalists and attempts to leave Israel proper to go to Bethlehem, which is in the West Bank.

The court's sentence was unexpected, and even the prosecution expected the court to hand down a suspended sentence, meant solely as a deterrent.

Vanunu's attorneys, Michael Sfard and Avigdor Feldman, said before the conviction was handed down that the terms of their client's parole order were unreasonable.

According to the verdict, "The order stemmed from the fact that the accused had hoarded in his memory classified information that has not been released, and the release of which could harm the security interests of Israel."

After the verdict was announced, Vanunu said that his conviction proves that Israel is still ruled, in effect, by the British mandate, because the law under which he was convicted is from that era.

"Maybe I need to turn to the queen or to Tony Blair in order to grant me justice," he said.