Israeli nuclear whistleblower Mordechai Vanunu (search) was indicted Thursday for violating the terms of his release from prison, the Israeli Justice Ministry said.

Vanunu was freed from an Israeli prison in April after completing an 18-year sentence for revealing secrets of Israel's atomic program to the Sunday Times newspaper in London.

Under the terms of his release, the former technician at the Israeli nuclear facility in the Negev desert town of Dimona was barred from leaving Israeli territory and contacting foreigners. The restrictions were in force for a year and their extension was expected to come up for consideration in coming weeks.

The Justice Ministry said Vanunu was being indicted for 21 cases of violating the release restrictions and one instance of attempting to leave Israel.

"It emerges that since his release Vanunu has violated (the terms of his release) imposed by the head of the Home Front Command (search) in a systematic fashion in that he exchanged information with foreigners and foreign residents with no prior authorization," the ministry statement said.

"Since his release Vanunu has maintained contact with numerous foreign journalists and even told some of them he was aware he was violating the terms of his release by meeting and exchanging information with them."

The 11-page indictment lists 14 prosecution witnesses, most of them police officers.

On numerous occasions, Vanunu has tested the limits of his release by granting interviews to foreign news media. He also was stopped by Israeli police on Christmas Eve while attempting to attend Midnight Mass in the West Bank town of Bethlehem (search), outside his permitted area of travel.

Since his release from prison, Vanunu has been living at a Jerusalem church compound.

Israeli authorities have said they fear Vanunu may have more nuclear secrets to share with the world. Vanunu, a Jewish convert to Christianity, has said he has nothing more to disclose and wants to leave the country.

Vanunu was convicted in 1988 after being captured in Europe and brought back to Israel by the Mossad intelligence service. His disclosures on the Dimona nuclear reactor led experts to conclude that Israel has the world's sixth-largest stockpile of nuclear weapons, including hundreds of warheads.

Israel has followed a policy of nuclear ambiguity, neither confirming nor denying it has such weapons.

Vanunu became a hero to peace activists for his role in unveiling Israel's nuclear program. In a September interview with The Associated Press, he said he wanted to replace his Israeli citizenship with a foreign one, perhaps Palestinian.

"In Israel, I am regarded as a traitor ... and since my release they are not respecting my human rights, my freedom of speech my freedom of movement," he said then.