Twenty five years ago, in 1973, I was responsible for an ITV film called The Unknown Famine which exposed Ethiopia as a crumbling empire stricken by mass starvation. Within Ethiopia the film aroused shame and anger. As a direct result, The Unknown Famine became the catalyst for the overthrow of a feudal emperor in favour of that gruesome dictatorship which soon became synonymous with the name of Mengistu.
The prisoner who now sought to indict me was, like his fellow inmates, incarcerated for his alleged part in Mengistu's reign of terror which finally ended eight years ago. Facing his indignation, I countered: "I hope you are joking." He wasn't.
The atrocities for which he and his fellow inmates are now collectively indicted can tempt the unwary into nostalgia for Haile Selassie. It is easy to forget that the emperor used to authorise public hangings, that his opponents were routinely tortured, that courtiers who fell from grace were not only jailed but frequently held in chains as well, and that concepts of justice, liberty and democracy were effectively outlawed from public debate. Against that background, a group of dissident army officers instigated a creeping coup against the emperor's faltering regime. To guard against a public backlash in favour of Haile Selassie (who was still widely revered), they contrived to obtain a copy of The Unknown Famine which they intercut with images of Africa's grand old man presiding at a wedding feast in the grounds of his palace. Retitled The Hidden Hunger, this film noir was shown round the clock on Ethiopian television to coincide with the day that they finally summoned the nerve to seize the Emperor himself.
As propaganda, The Hidden Hunger had precisely the required effect. Not only the armed forces, but - with few exceptions - the peasants, the urban middle class, and the students gave enthusiastic support to a military dictatorship that promised to wage war on capitalism and imperialism and to liberate the toiling masses from the yoke of feudalism. Alongside this pernicious gobbledegook (which incorporated such choice slogans as "Revolutionary Motherland Or Death"), The Hidden Hunger was a potent weapon: wheeled out at mass rallies all over Ethiopia to reassure the "masses" that the new regime was indeed on the side of the angels. Tens of thousands of young people, intoxicated by the televisual imagery of starvation and the rhetoric of revolution, signed up for Mengistu's cause and, without a second thought, became footsoldiers for genocide. Within five years the "red terror" - as the slaughter was officially known - accounted for at least 100,000 lives.
My accuser may or may not be guilty as charged but at least he is still alive. When he complained that he had been incarcerated without trial for seven years - "they want us to die here" - I was reminded of the day, 24 years ago, when 60 of the former Emperor's officials were executed by firing squad, without charge or trial, simply because Mengistu became impatient with the commission of inquiry that he had himself set up and opted for a little "revolutionary justice" to speed things up. In 1998, the special prosecutor's office may be inept, arthritic and even corruptible, but at least it operates within a constitutional framework.
For my alleged part in the downfall of the Emperor, I became - unwittingly - something of a local hero. In this guise, I was free to witness and record Ethiopia's revolutionary torment until, in 1977, I could no longer restrain my revulsion. As a result, I was denounced as a traitor and declared persona non grata. By the time I was allowed back, a decade later, Mengistu's charnel house was, blessedly, about to be razed, but Ethiopia was economically and politically bankrupt.
The new government, which came to power in 1991, promised democracy and human rights for all. The prime minister, Meles Zenawi, is a former guerrilla leader who is greatly admired in Western chancelleries as one of the "new men" of Africa. But his record has been under intense, often critical, scrutiny by any number of international bodies. Under his leadership, Ethiopia is now a far more open society than it has ever been. Today, friends who had been too frightened to see me in the Eighties now speak without any constraint and - a gratifying irony - they debate openly the extent to which the government of Meles Zenawi uses the power of the state to suppress his critics.
Similarly, the chairman of the commission of inquiry, whose proceedings were so horrifically aborted by Mengistu's executioners more than two decades ago, has now resurrected himself as the Chairman of the Ethiopian Human Rights Council. When Professor Mesfin Wolde-Mariam, a brave man and an eminent academic, fulminates against the "systematic" violation of human rights by the present authorities, his allegations cannot be ignored: he produced compelling evidence that extra-judicial killings, "disappearances", torture and illegal detention still persist. However, when he argues that there is now little to choose between Meles and Mengistu, the comparison seems grotesque. After all, as I remind him, he is now perfectly free to make precisely those charges.
A similar paradox surrounds the freedom of the press. Upwards of 70 private newspapers and magazines are now on sale in Addis Ababa. Many of them are scurrilous. Some of them are personally abusive of the prime minister. A few promote ethnic hatred and - none too obliquely - terrorist subversion as well. None of them is censored, but news vendors are routinely harassed and editors are frequently detained in jail on a variety of trumped-up charges. Hard on the heels of Professor Mesfin, Amnesty International has joined the fray to condemn the government for suppressing the free expression of legitimate political dissent. Clearly irked by this criticism, Meles acknowledges that there are "flaws and blemishes" but claims that Amnesty has neither the means nor the time "to verify its allegations". This uncharacteristic show of prime ministerial hubris springs - I suspect - from deep frustration at the failure of Ethiopia's critics to place his dilemmas in historical perspective and at their refusal to appreciate the fragility of his authority as he seeks to lead his divided country from dictatorship towards democracy.
Ethiopia is culturally diverse and politically backward. Traditionally ruled by rival warlords who, until very recently, imposed their authority with the spear and the rifle (mediated from time to time by the centre with severe military repression), its 60 million citizens are among the poorest on earth. They have never known freedom or democracy. Now, in an act of calculated desperation, Meles has tried to steer Ethiopia away from the persistent threat of terminal implosion by redrawing the constitutional map of the new federal state along ethnic lines.
It is a high-risk strategy. Although his party emerged all-powerful from Ethiopia's first quasi-democratic elections in 1995, Meles has started to devolve real power, which could easily be seized by rivals to destroy his survival strategy. As yet, Ethiopia is far from being a genuinely free society. Human rights are abused and democracy has yet to take root.Yet, when the prime minister volunteers that he looks forward to the day when he is removed from office via the ballot box and insists "either we have democracy or we disintegrate", I think he means it. I hope so: he is Ethiopia's best bet yet.
Jonathan Dimbleby's documentary `An African Journey' will be shown tonight at 10.40pm on ITV