The construction of a huge dam in Ethiopia and the introduction of large-scale agricultural businesses has been controversial - finding out what local people think can be hard, but with the help of a bottle of rum nothing is impossible.

After waiting several weeks for letters of permission from various Ethiopian ministries, I begin my road trip into the country's southern lowlands.

I want to investigate the government's controversial plan to take over vast swathes of ancestral land, home to around 100,000 indigenous pastoralists, and turn it into a major centre for commercial agriculture, where foreign agribusinesses and government plantations would raise cash crops such as sugar and palm oil.

After driving 800km (497 miles) over two days through Ethiopia's lush highlands I begin my descent into the lower Omo valley. Here, where palaeontologists have discovered some of the oldest human remains on earth, some ancient ways of life cling on.

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Some tourists can be found here seeking a glimpse of an Africa that lives in their imagination. But the government's plan to "modernise" this so-called "backward" area has made it inaccessible for journalists.

As my jeep bounces down into the valley, I watch as people decorated in white body paint and clad in elaborate jewellery made from feathers and cow horn herd their cows down the dusty track.

I arrive late in the afternoon at a village I won't name, hoping to speak to some Mursi people - a group of around 7,000 famous for wearing huge ornamental clay lip plates.

Image copyright ALAMY

The Mursi way of life is in jeopardy. They are being resettled to make way for a major sugar plantation on their ancestral land - so ending their tradition of cattle herding.

Meanwhile, a massive new dam upstream will reduce the Omo River, ending its seasonal flood - and the food crops they grow on its banks.

It is without doubt one of the most sensitive stories in Ethiopia and one the government is keen to suppress.

Human rights groups have repeatedly criticised schemes like this, alleging that locals are being abused and coerced into compliance.

I'd spoken to local senior officials in the provincial capital of Jinka, before travelling into the remote savannah.

The suspicion is palpable as the chief of the south Omo zone lectures me. Local people and the area's reputation have been greatly harmed by the negative reports by foreigners, he says.

Eventually a frank exchange takes place and I secure verbal permission to report on the changes taking place in the valley.

The Gibe III Dam

Image copyright AFP Image caption The Omo River

Situated approximately 300km south-west of the capital Addis Ababa, the dam is 246m high

Work started in July 2006 and was estimated to take 118 months (nearly 10 years)

The government says it will provide much needed-power and help develop the country's economy

Authorities say no-one has been forced from their home

It seems prudent to let the Mursi tribe and attendant police warm to my presence before I start asking questions. After all, I have the whole evening.

But a brief chat with the tribe ends abruptly with the entrance of a police officer, wearing a replica Manchester United football shirt, vehemently waving a dog-eared copy of the country's constitution.

I am prohibited from talking to anyone and must immediately climb back into my jeep, drive back up the mountain and return to Jinka, he says.

As often in Ethiopia, he doesn't explain exactly why.

I object to driving through the wilderness at dusk on safety grounds and so a compromise is reached: I will pitch my hammock outside the police station, a short stroll away from the village, with armed guards watching my every move.

The political boss of the zone comes on the two-way radio. "This is house arrest," I protest. "No, just a misunderstanding," he replies.

The prospect of returning home without interviews is unthinkable. My ruse is to distract my captors.

I sit them down for a meal of pasta and vegetables - and brimming beakers of spiced rum - in front of my laptop, which is playing an Ethiopian comedy.

After saying good night I strike out through the scrubland.

I run without sense of direction through bush and bog, crawl under fences, and negotiate large herds of noisy cattle. I have to find a village elder I met earlier, and interview him before policemen and their flashlights turn up.

So I am relieved to stumble on two boys milking their cows in the moonlight. They lead me to the elder's hut. The sound of so many rudely-awakened animals in our wake fills me with dread that searchlights are heading our way.

The moment arrives. I squat in front of the elder inside his mud dwelling, surrounded by his sleeping companions: several cows, a goat and a cat. My dictaphone is poised to record truths heard by few journalists in this media-muzzled region.

I ask him in broken Amharic what is going on. He tells me: "The government is telling us to sell our cattle and modernise like townspeople - they say our land is the property of the sugar corporation. We have not been asked what we want or need.

"If we do not accept the resettlement plans, we'll be taken to jail. How can we survive if we have no access to land, cattle or water?"

I promptly thank the elder for his time, apologise for disrupting his evening and head back to my open-air jail.

On reaching my hammock I find several dozing policemen and an empty bottle of rum. Mission accomplished.

The Mursi people

Image copyright AFP

About 10,000 Mursi people live in Ethiopia

Traditionally insert pottery plates known as debhinya in the lower lips of young women

They live in an area surrounded by the rivers Mara, Omo and Mago, which flow into Lake Turkana

Mursi territory was incorporated into Ethiopia during the reign of King Menelik II in the 19th Century

Source: Oxford University Department of International Development

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