It takes an hour to make a kilo of cocaine paste

It took a couple of hours to get there by mule. At first we went through tropical forest.

Monkeys chattered in the distance. High up in the trees I caught the flash of red and blue wings. 'They're macaws' said Francisco, my guide.

Then we came out of the forest and up into the mountains.

'Devastation'

As we made our way up, I saw the smallholdings cultivated by the peasant families.

All my crops were destroyed - the poison even got into the soil

Colombian farmer Chairo

There were patches of cassava, maize and bananas, and here and there a strip of coca.

To my untrained eye, the plants looked like young coffee bushes, with the same bright green foliage.

Eventually we came round a bend in the mountains and looked down at a scene of devastation.

Withered banana trees, with their large leaves burnt brown. Dead stalks of maize. Stunted cassava plants.

Six weeks earlier, Francisco told me, army planes had swept over the hillside, spraying all the crops with a powerful herbicide.

Francisco called out over the valley to Chairo, the peasant we were visiting.

Poisoned well

We made our way carefully down the hillside to Chairo's hut.

He and his wife, Magola, told us what had happened.

Coca is more lucrative than other crops

'We had no warning', said Chairo. 'The planes arrived early one morning. Whoosh, like this. We raced up the hill, me, Magola and our three children.

"We watched as they sprayed everything in sight. All my crops were destroyed. The poison even got into the soil," he said.

Chairo took me to a patch of cassava behind his hut. He dug up a tuber of cassava and broke it in half.

"Look," he said. "It's all rotten."

The herbicide had got into the well water too and they had all been ill.

"Look at our daughter," said Magola. "It's her 18th birthday today. And all she can do is lie in the hammock. She's still got diarrhoea and is passing blood."

Cocaine paste

Ironically, the crop that fared best was the coca. The bushes were already sprouting again.

Chairo said he had planted a single hectare of coca.

"It's the only crop that brings in money," he said somewhat defensively. "We're so far from the market that I can't sell my cassava and bananas."

If farmers cannot survive, one option is to join rebel fighters

Chairo then took us round to meet his neighbour, Pedro. He is the one who manufactures coca paste from the leaves.

Pedro pointed to six big drums in the back of his hut.

He tried to tell me how he makes the paste, but he slurred heavily over his words.

And then slumped back in his hammock. He was clearly stoned out of his mind.

I could not tell whether he was like that from the acids he breathes in during the processing, or whether he himself was consuming the coca paste he makes.

Chairo took over. "He mixes the leaves with cement, petrol, sulphuric acid and ammonia," he said.

"You need a lot of coca leaves to make one kilo of paste but it only takes you an hour to make it."

Destroyed livelihood

Saying goodbye to Chairo and his family, I made my way down the hillside on the back of my mule.

Chairo says he's too far from the market to make money from bananas

It was a beautiful evening. Birds were making those extraordinary liquid cries that you only hear in the rain forest. Hundreds of frogs were croaking.

I thought about Chairo and his family. I know he had been cultivating coca, an illegal crop. But what good did it do to destroy his livelihood?

Chairo said he was thinking of moving away, to the nearest town. But what would he do there?

Colombia has one of the highest rates of unemployment in Latin America. Another option - although not one that Chairo openly admitted to - was to join the guerrillas.

Increasing production

The spraying of the crops is funded by the United States. It is part of Plan Colombia, America's ambitious anti-narcotics programme.

The policy is clearly failing. Afraid of losing part of their crop, some peasant farmers have even been planting more coca than usual - so coca production is actually increasing.

And a new group of peasant farmers is beginning to hate the Americans for destroying their livelihoods.

Colombia already has three armed groups, including the left-wing FARC, classified as 'terrorist' by the US State Department.

Washington is calling on the Colombian government to take tougher action against the insurgents, yet it is America's own policies that are generating recruits for these movements.