This is a tale of two whistleblowers. Let’s begin with Edward Snowden. The former US National Security Agency contractor has been hailed by the liberal left for exposing mass surveillance on an “almost Orwellian” scale (to borrow a line from a US district judge). He was voted person of the year for 2013 by Guardian readers and took the runner-up spot – behind the Pope! – in Time magazine’s annual list. On 25 December, Snowden appeared on Channel 4 to give the “alternative Christmas message”, warning viewers that the types of surveillance mentioned in Nineteen Eighty-Four “are nothing compared to what we have available today”.

On Christmas Day, another whistleblower spoke out – but inside an Israeli courtroom, rather than on British television. “I don’t want to live in Israel,” declared Mordechai Vanunu, who served 18 years behind bars for blowing the whistle on Israel’s nuclear secrets. “I cannot live here as a convicted spy, a traitor, an enemy and a Christian,” he told Israel’s High Court, in English, having vowed not to speak Hebrew until he is allowed to leave the country.

Vanunu was jailed in 1988 for leaking details of his work as a technician at a nuclear facility near Dimona to the Sunday Times two years earlier. On 29 December 2013, the court rejected his petition, on the grounds that he continues to possess information that could jeopardise Israel’s national security. Andrew Neil, the former editor of the Sunday Times, disagrees. “He told us everything,” Neil told me. “We drained him dry.”

Neil calls Vanunu’s revelations the biggest scoop of his 11-year editorship of the Sunday Times. “Everyone knew Israel had the bomb but what we didn’t know was the huge extent of its nuclear facilities and also its ability to make the hydrogen bomb,” he tells me. “[The Vanunu story] told the world that Israel was basically the sixth nuclear power.”

As a result, Vanunu has been persecuted by the Israeli state for almost three decades. For the first 11 years of his 18-year prison sentence, the former nuclear technician was held in solitary confinement in a nine-foot-by-six-foot cell. His treatment was condemned by Amnesty International as “cruel, inhuman and degrading”; Vanunu has described it as “barbaric”.

This barbarism has continued since his release in 2004. Vanunu has been subjected to restrictions on his freedom of speech and movement. He is prevented from talking to foreign journalists, visiting foreign embassies or owning a mobile phone and has repeatedly been placed under house arrest for breaching these strictures; hence his repeated attempts to try to leave the country.

It is worth repeating: in Israel, which styles itself as the “only democracy in the Middle East”, it is a crime for whistleblowers to meet foreigners. So, where’s the outrage? Where are the human rights activists? The liberal interventionists? Their silence is a stark reminder that it is far easier to champion the cause of an American critic of the US than an Israeli critic of Israel. (Especially when that critic is a Jewish convert to Christianity, as Vanunu is, and has dared to say: “A Jewish state is not necessary.”)

Not a single national newspaper in the UK covered Vanunu’s recent appearances in court. Over the past few years, the British press has deigned to mention his name on only a handful of occasions. Little has changed: “The day after we published the [Vanunu] story, all the British newspapers either ignored the story or rubbished it,” Neil recalls.

Vanunu has been ignored and forgotten. Those who criticise Snowden for fleeing to Russia by way of Hong Kong don’t have a clue. It is only because Snowden went on the run and, crucially, appeared on television and did interviews that the rest of us have been able to benefit from his information. The Israelis, as Neil notes, “feared the propaganda effect” of Vanunu. The Sunday Times had lined up a series of TV interviews for him, but before he could do them he was drugged and kidnapped by Mossad and taken back to Tel Aviv for trial.

Vanunu recently compared himself with Snowden, saying that the former NSA analyst “is the best example for what I did 25 years ago – when the government breaks the law and tramples on human rights, people talk . . . He speaks for everyone and that’s what I did.”

Like Snowden, Vanunu isn’t a traitor. He is a whistleblower who, in Neil’s words, “took the view that if Israel should have nukes, that should be a matter of public record [and] debate”. He could have sold Israel’s nuclear secrets to the highest bidders in Moscow or Damascus. He didn’t. The Vietnam war whistleblower Daniel Ellsberg calls Vanunu “the pre-eminent hero of the nuclear era”. “More Vanunus are urgently needed,” he wrote in the Los Angeles Times in 2004. “That is true not only in Israel but in every nuclear weapons state, declared and undeclared.”

Indeed, it is. Double standards, however, abound. Can you imagine how the west would treat an Iranian Vanunu? How hysterical do you think the response would be in London or Washington – or Tel Aviv! – if an Iranian nuclear scientist were to come forward with, say, photos of secret warheads, only to be locked up by the mullahs and sentenced to solitary confinement?

For 27 years, Vanunu has been deprived of his liberty – for blowing the whistle, for telling the truth. It is a moral and geopolitical disgrace. We cannot afford, in good conscience, to forget the plight of Israel’s Snowden. To quote the Northern Irish Nobel peace laureate Mairead Maguire, “We cannot be free while he is not free.”