The Peruvian government says it is committed to eradicating the coca leaf, from which cocaine is made - but a walk in the jungle suggests that for cash-strapped farmers, it is not an easy choice.

I should probably have listened just a little more carefully when the farmer answered my question.

I had asked if she would show me where her hidden coca plantation was - and what she said was: "Yes, of course, but it will mean a bit of walking."

Now, I like walking, I walk for pleasure. But what a Peruvian farmer means by a "bit of walking" turned out to be rather different from what I mean.

We were in the region known as the High Amazon. It is breathtakingly beautiful. Green, lush hillsides and steep wooded valleys, where the foothills of the Andes meet the Amazon jungle. Traditionally it has been one of the main production centres for Peruvian cocaine.

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We set off, following the farmer, her husband, and their dog, down a steep muddy path.

He carried a machete, and hacked away at the undergrowth to clear a way for us down the side of the valley. After I had already landed on my backside half a dozen times, he cut a stout pole to help me keep my balance.

After maybe 40 minutes or so of slipping and sliding, we reached the bottom. And, as is often the case at the bottom of valleys, there was a river. Not a huge river, admittedly, but a river nonetheless, and we obviously were going to have to cross it.

There was no bridge, but there was a tree trunk. By this time, I was carrying two stout poles, plus a backpack, but I was helped across by the farmer's husband, who gripped my hand tightly as I inched along the tree trunk, and their dog, splashing excitedly through the water, tail wagging, egging me on.

Clambering up the other side was a lot easier than sliding down had been - and when we eventually reached the coca clearing, I finally got a chance to catch my breath and to talk to our companions.

I never learnt their names - they thought it was probably better for all of us if they remained anonymous.

After all, as far as the authorities were concerned, they had given up their illegal coca cultivation and were now growing coffee and bananas. Which to be fair, they were, but as well as the coca, not instead of it.

So we sat, and we talked. She was wearing a pink T-shirt, a baseball cap, faded brown trousers and gumboots. Stockily built, in her 40s, and defensive about continuing to grow a crop that her government says she should not be growing.

"We cannot make a living growing just coffee and bananas," she said. "It takes years for those trees to become established, so what should we live on? We get no help from the government, so we have to grow the coca."

She would love to stop, she said - but that may have been because she knew that was what she was meant to say.

Yes, she said, she knows what happens to the coca leaves after she has sold them, and she knows that criminal gangs control the trade in cocaine.

"I am only growing a very small amount," she said. "It really does not make any difference."

The coca growers of Peru insist that they are not the ones who get rich from the cocaine trade.

Although I did meet one man - a former coca grower who has now switched entirely to growing cocoa, instead of coca - who admitted that in his former life, he did make a very good living.

He spent his ill-gotten gains, he told me, on gambling and drinking and women. Now, as a solid law-abiding citizen, with three jail terms behind him, he says he spends his more modest income on looking after his family.

"I do not have as much money as I used to have," he said. "But I sleep better at night. I do not have to worry any more about the police knocking on my door."

Image caption Drug enforcement police set plantations alight

Coca has been grown in Peru for thousands of years.

If you chew the leaves, or use them to make tea with, they act as a mild stimulant, a bit like a strong cup of coffee.

I bought a small bag of coca leaves, quite openly, on a street corner in the central Peruvian town of Tingo Maria.

It may sound like the name of an exotic liqueur - in fact, it is a thriving, bustling place, its streets are jammed with Chinese-made motorcycle taxis - and it owes its prosperity, almost entirely, to coca.

They are trying to adapt. In a smart, New York-style coffee bar, I was offered a very good cup of espresso, made with locally-grown beans.

The hope is that it is coffee, not coca, on which the region's future prosperity will be built.

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