By Richard Hamilton
BBC News, Morocco
Morocco has dramatically reduced its production of cannabis.
Olive trees are being grown as an alternative to cannabis
The United Nations Office on Drugs and Crime (UNODC) says the north African country, which was the biggest supplier of hashish in the world, has now cut production of the crop by almost 50% over the past three years.
The Moroccan government says it plans to completely eradicate cannabis by 2008.
We drove into Morocco's cannabis country: the Rif mountains, where they have been growing cannabis, or "Kif" as it is called, since the 15th Century.
The landscape is imposing - craggy peaks and ridges look down onto luminous green valleys.
I was travelling with Alessandro Boccoli, an agricultural advisor to the provincial government.
I asked him how difficult it was to police this area.
"Yes of course access is very difficult, not only for the police, for everybody, you have to know all the routes," he said.
"The cannabis plant is well adapted to the environment here, to the climate, the conditions and even to the agricultural ways of the people."
We came to a ridge where there were some scattered fields and where the odd cannabis plant was poking out through the rocks.
Here men were pruning olive trees, which are being grown as an alternative to the cannabis crop.
Local farmer Mohamed Garrouj is keen to try it because he's already suffered the consequences of growing the illegal crop: "I used to grow cannabis but I was put in jail because of it, for eight months.
"Now that's all over, I don't grow it anymore. It's not just me, whole villages have been put in jail for it!"
Clamping down on cannabis production is not easy in Morocco
As well as more stringent policing, the authorities have improved their security measures along the coast. For example they have installed the latest hi-tech scanners at the ports.
It is thought that the urgency with which they are now acting stems from international pressure to address the drug problem.
Some intelligence experts believe the militant group which bombed trains in Madrid in 2004 was largely funded by cannabis trafficking.
Khalid Zerouali from the Moroccan Interior Ministry says it has not been easy clamping down on cannabis production.
"It's very difficult exercise, but what we do is we eradicate. We destroy the crop in the field, involving with us, the civil society, the local population, and we try to give them help, so they can immediately start growing something else," he told me.
Walking in another even more remote part of the Rif mountains, I could see some fields where the seeds of cannabis were being sown.
Despite the government crackdown, it was quite easy to find people who admitted growing cannabis.
"The gendarmerie come here and tell us not to grow cannabis, but how can we live?" asked Mohammed, another local farmer.
"Ever since we started growing cannabis we have been afraid, but what can we do, we're just trying to earn a living, for us and for our children.
"If the government catch us with just a little bit they arrest us. We are very worried."
The UNODC says the biggest challenge is finding other ways farmers like Mohammed can survive.
"There have been lots of past attempts to find alternative crops, but they haven't always worked, because cannabis is a crop that commands such an inflated price," explained Abdeslam Dahmane from development agency Targa which works closely with the UNODC.
"There have been attempts at introducing apples, vines and things like that but they haven't really addressed the problem.
"It's not a question of replacing cannabis with apples, vines or avocados. The question is replacing the incredibly dynamic economy of cannabis, with an equally dynamic economy - that is also legal."
Chefchaouen lies in the heart of the Rif mountains.
Hashish is easy to come by in the hippy haunt of Chefchaouen
In the medina, people sell all sorts of vegetables and fruits amid the narrow cobbled alleyways of whitewashed walls and blue doors.
Chefchaouen has been a favourite haunt of hippy travellers and backpackers for years, as hashish is easier to buy here than in much of Europe.
Khalid Zerouali from the Moroccan Interior Ministry says Europe's seemingly insatiable demand for cannabis is still the main obstacle to eradicating it completely.
"In terms of supply I think Morocco has done a lot.
"But we need also to master the demand. Last year about 22m people consumed cannabis in Europe. That makes it very difficult.
"In terms of making the psychological costs so high for the traffickers I think the seizures - last year 88 tonnes of cannabis - are very important. The component that is very difficult for us because we don't master it, is demand.
"I think in Europe there has to be an awareness of how to tackle that demand."
But demand is not about to drop away, so the successes of the Moroccan government in reducing supply may be hard to sustain.
It looks as if it will take more than olive trees to persuade some of the most impoverished farmers in this region to give up their most lucrative crop.