The Arab Spring began in the Western Sahara. In late 2010, the indigenous Saharawi population of this territory demonstrated against the occupying Moroccan authorities. Their demonstrations were violently put down. Eleven Saharawis were killed.

But this is one part of the Arab Spring that western governments don't want to talk about. And their silence, and the UN's complicity in it, is why that repression continues, and a terrible injustice is perpetuated.

Western Sahara was invaded by Morocco in 1975. Its indigenous population was, in contemporary parlance, ethnically cleansed. Around 150,000 of those driven out remain in isolated refugee camps in the Algerian Sahara: in tents, in the middle of the desert (I have been there; it is grim). The Saharawis, fought back in a guerrilla war that lasted until a ceasefire in 1991. The centerpiece of that ceasefire, repeatedly endorsed by the UN and international community, was that there would be a referendum for the people of Western Sahara to decide the future of the territory, and in particular whether it would be a independent state.

That referendum has never taken place. Western Sahara remains Africa's last colony. Morocco successfully delayed and manipulated the UN organization of the referendum until it ground to a halt. The UN attempts to get "the parties" to agree on a way forward. There has been no progress: Morocco refuses even to discuss a referendum. For this obstruction, Morocco pays no price whatsoever.

There have been systematic human rights abuses by Moroccan forces in the occupied Western Sahara, documented by Amnesty International (pdf), Human Rights Watch (pdf) and the UN high commissioner for human rights (pdf). This last report, never published at Morocco's insistence, recommended in 2006 that there be a permanent human rights monitoring presence in the territory. Despite this clear recommendation, Morocco's allies at the UN – in particular, France – have successfully blocked its implementation.

Western governments have, in recent months, paraded their new-found support for human rights and democracy in the Middle East. France's President Sarkozy has pressed the flesh in Libya and Tunisia, reveling in his status as liberator of the downtrodden. But you won't see him in the Western Sahara, and he won't mention the plight of the Saharawi people when he shakes hands with Morocco's king, his ally, Mohamed VI.

This week, the whole imbroglio will be discussed again at the UN security council. It's important to observe the subtle but pernicious ways in which injustice is perpetuated at the UN.

For instance, it has been revealed in recent weeks that the UN allows its own reports on Western Sahara to be doctored by Morocco, its occupier. No one, from Ban Ki Moon downwards, lifts a finger to stop it. The UN released successive and different versions of the report, explicitly indicating Morocco's "editing", including its removal of references to the Moroccan flag flying over the UN mission headquarters (a figurative symbol of what is really going on) and any reference to the mission's original mandate to organize the referendum.

Recently, the UK and South Africa, to their credit, have led efforts to institute human rights monitoring, and try to push for resolution to this long-lasting dispute. France continues to block. Its obstruction is unreported; it is carried out in small rooms at the UN, where French diplomats softly declare that they will not permit human rights "language" in the resolution. Their press spokesman tries not to answer questions about it from the few journalists who take an interest ("where's the story?" they ask, "it's been going on for years").

Morocco has been a good ally of the US, including by receiving prisoners for torture under the program of "extraordinary rendition": one of them a British resident, whose genitals were cut with razors by Moroccan government torturers. Today, Morocco has been quick to put itself on the right side of the Arab Spring, by supporting Nato in Libya. The kingdom has bought substantial lobbying muscle in Washington, including the former US ambassador to Rabat.

Hillary Clinton walks an awkward path on this issue, to put it politely, although the US, as this month's president of the UN security council, could play a decisive role. She has made speeches applauding the bravery of women who fight for human rights around the world. But she never mentions Aminatou Haidar, an extraordinary 42 year-old, who has been tortured, held in solitary confinement for years, and has endured 32 days of hunger strike in support of freedom for the Saharawi people. If Hillary Clinton were to meet this extraordinary and heroic woman, who has won numerous human rights prizes, I wonder if she would maintain the laissez-faire US policy that allows continuing repression and the suffering of thousands of refugees waiting for justice in the Sahara desert.

The personal is political. It is ordinary human beings like Aminatou Haidar who suffer in the Western Sahara. And the policies that maintain their suffering are decided by women like Secretary Clinton and the diplomats whom I know to be, at heart, decent people. Why this decency is suspended in Western Sahara is a case study in how diplomacy remains in many ways a morally corrupt business. It does not have to be this way.

• Disclosure notice: Independent Diplomat, the non-profit diplomatic advisory group, which Carne Ross heads, advises the Polisario Front, the representatives of the Saharawi people

