Vanunu spent 18 years in prison, including more than 11 in solitary confinement, though no such restriction is mentioned in Israel's penal code, nor imposed by his verdict. Released from prison in 2004, he was further subjected to a broad array of restrictions on his speech and his movement, and arrested several times for violations of his parole terms, giving interviews to foreign journalists and attempting to leave Israel. He claims to have suffered from "cruel and barbaric treatment" at the hands of prison authorities, and suggests that these would have been different if he had not converted to Christianity.<ref>{{cite news|title=Israeli nuclear spy released|url=https://www.cnn.com/2004/WORLD/meast/04/21/israel.vanunu|work=CNN|date=21 April 2004|access-date=12 February 2009}}</ref>
In 2007, Vanunu was sentenced to six months in prison for violating terms of his parole. The sentence was considered unusually severe even by the prosecution, who expected a [[suspended sentence]]. In May 2010, Vanunu was arrested again and sentenced to three months in jail on a charge that he had met foreigners, in violation of conditions of his 2004 release from jail. In response, [[Amnesty International]] issued a press release in July 2007, stating that "The organisationorganization considers Mordechai Vanunu to be a [[prisoner of conscience]] and calls for his immediate and unconditional release."<ref>{{cite web|url=http://news.amnesty.org/index/ENGMDE150442007|title=Israel: Mordechai Vanunu sentence clear violation of human rights|publisher=[[Amnesty International]]|date=2 July 2007|url-status=dead|archive-url=https://web.archive.org/web/20070710201838/http://news.amnesty.org/index/ENGMDE150442007|archive-date=10 July 2007}}</ref>
Vanunu has been characterisedcharacterized internationally as a [[whistleblower]]<ref>{{cite news|url=http://news.bbc.co.uk/nol/shared/spl/hi/programmes/correspondent/transcripts/17_03_2003.txt|title=Correspondent: Israel's Secret Weapon (transcript)|date=17 March 2003|publisher=BBC}}</ref><ref>{{cite news|url=http://www.haaretz.com/print-edition/news/capturing-nuclear-whistle-blower-was-a-lucky-stroke-agents-recall-1.120228|title=Capturing nuclear whistle-blower was 'a lucky stroke', agents recall|work=[[Ha'aretz]]|date=12 November 2006}}</ref> and by Israel as a traitor.<ref>{{cite web|url=http://www.jewishworldreview.com/0404/stephens_vanunu.php3|title=The meaning of Vanunu|work=Jewish World Review|date=26 April 2004|access-date=12 November 2006|archive-date=24 February 2021|archive-url=https://web.archive.org/web/20210224155548/http://www.jewishworldreview.com/0404/stephens_vanunu.php3|url-status=dead}}</ref><ref>{{cite news|url=http://www.smh.com.au/articles/2004/04/21/1082530235940.html?from=storyrhs|title=Vanunu: traitor or prisoner of conscience?|work=[[The Sydney Morning Herald]]|date=22 April 2004}}</ref><ref>{{cite news|url=http://www.jewishsf.com/content/2-0-/module/displaystory/story_id/22200/edition_id/448/format/html/displaystory.html|title=Vanunu: Hero or traitor?|work=JWeekly|location=San Francisco|date=23 April 2004|url-status=dead|archive-url=https://archive.today/20121208161538/http://www.jweekly.com/article/full/22425/vanunu-hero-or-traitor/|archive-date=8 December 2012}}</ref> [[Daniel Ellsberg]] has referred to him as "the preeminent hero of the nuclear era".<ref>{{cite web|url=https://www.latimes.com/archives/la-xpm-2004-apr-21-oe-ellsberg21-story.html|date=21 April 2004 |work=[[Los Angeles Times]] |title=Nuclear Hero's 'Crime' Was Making Us Safer |first=Daniel |last=Ellsberg|access-date=22 April 2020}}</ref> In 1987, he was awarded the [[Right Livelihood Award]] for "his courage and self-sacrifice in revealing the extent of Israel's nuclear weapons program".<ref>{{Cite news |last=Campbell |first=Duncan |date=2004-04-16 |title=The Guardian profile: Mordechai Vanunu |language=en-GB |work=The Guardian |url=https://www.theguardian.com/world/2004/apr/16/israel |access-date=2023-11-03 |issn=0261-3077}}</ref>