The government is refusing to let Mordechai Vanunu leave the country for three days to speak at a conference in London and address the British parliament.

Vanunu, who spent 18 years in prison for giving information about Israel’s nuclear program to the foreign media, was invited by Amnesty International to address a conference on freedom of information and protecting whistle blowers. In honor of the 10th anniversary of his release from jail, he was also invited to address British parliamentarians. He therefore sought to travel to London for three days, June 17-19. But Interior Minister Gideon Sa’ar and Attorney General Yehuda Weinstein refused to approve the trip.

Vanunu therefore petitioned the High Court of Justice against their decision last week.

Since leaving prison in June 2004, the nuclear technician has been barred from leaving the country or from speaking to foreigners without permission from the Shin Bet security service. These orders have been extended year after year, and the High Court has rejected seven successive petitions against them. In the most recent such ruling, in December 2013, Justices Asher Grunis, Miriam Naor and Isaac Amit said the classified material they were shown proves that Vanunu “still has a treasure of classified information and hasn’t recanted his intent to disseminate this information.”

In last week’s petition, Vanunu’s attorney, Avigdor Feldman, reiterated the argument he has made in previous petitions: that after so many years, Vanunu’s information is no longer much of a threat to national security. “The information about Israel’s nuclear capabilities that has been published since the petitioner’s release is incomparably greater, both quantitatively and qualitatively, than anything the petitioner could add today, more than 20 years after he stopped working at the Dimona nuclear reactor,” Feldman wrote.

Moreover, Feldman argued, letting Vanunu go abroad would do less harm to national security than refusing to let him, because, he said, the petitioner’s failure to appear at the Amnesty conference and the British parliament “would spark international protests against this severe administrative restriction on Citizen Vanunu.”

The travel ban, Feldman continued, constitutes an additional punishment on top of Vanunu’s sentence. “It’s true the petitioner was released from jail, but his freedom is still limited,” the petition said. “This is a harsh punishment that has been imposed on the petitioner. It’s not enough that he served a lengthy prison sentence; now, he is restrained, and his freedom limited, as if he hadn’t finished serving his sentence.”

Feldman told Haaretz that to the best of his knowledge, the restrictions imposed on Vanunu have no precedent either in Israel or the rest of the free world. The ban on talking with foreigners without the Shin Bet’s permission “would surely be acceptable in North Korea, but not in a country that defines itself as the only democracy in the Middle East,” he charged.

He also blasted the High Court for having approved these restrictions every year for 10 years on the basis of information that neither he nor his client were permitted to see, “and about which it’s doubtful that any of the Supreme Court justices understood anything,” but which they nevertheless accepted as proof that “Vanunu, who worked at the Dimona nuclear reactor 40 years ago, knows information that would almost certainly endanger Israel’s security.”

The state counters that Vanunu’s motivation to undermine national security hasn’t waned, and the information he has is still relevant. Because of this, Sa’ar wrote in his rejection of Vanunu’s request, “no restriction or guarantee to which your client might agree has the power to protect the State of Israel and its residents from the damage your client’s departure from Israel is liable to cause – damage that your client has more than once expressed his desire to cause if allowed to leave the country. Your client retains the ability to cause such damage, which would be irreversible, via the information in his possession that hasn’t yet been published, and which, as has been proven in court, is still relevant even today.”

The Justice Ministry said that in accordance with the court’s instructions, it would file a response to the latest petition by June 10.