200 players gathered in Tel Aviv for Canna Tech, an international conference on the drug

With its moat, wall, barbed wire, armed guards and security cameras, the facility could be mistaken for a military base if it weren't for the pungent odor of marijuana in the air.

Here, on the outskirts of a quiet village in northern Israel, 50,000 plants of 230 varieties grow at the country's second-largest medical cannabis plantation.

"For cannabis, we are in the promised land with a good climate, 300 days of sunshine each year and perfect levels of humidity," said Tamir Gedo, head of BOL Pharma, a company authorized by the Israeli health ministry to grow and distribute medical cannabis.

The recreational use of cannabis is illegal in the Jewish state, but for the past 10 years its therapeutic use has not only been permitted but also encouraged.

Last year, doctors prescribed the herb to about 25,000 patients suffering from cancer, epilepsy, post-traumatic stress and degenerative diseases.

The purpose is not to cure them but to alleviate their symptoms.

The use of cannabis in medicine divides doctors around issues of addiction and behavioral problems such as aggression.

Nevertheless, it has long been known to revive lost appetite and to help in treating sleep disorders, anxiety and inflammation, its supporters say.

They say much research remains to be done but it is advancing faster in Israel, where authorities allow human clinical trials, than in many other countries.

Entrepreneurs, investors and researchers are increasingly entering the business and searching for the holy grail of medicinal marijuana: a purified form of the drug with minimal side-effects and which can be administered in accurate doses.

Inside the fortified premises of Breath Of Life Pharma are laboratories and greenhouses, with each plant monitored by software that remotely controls its biochemical parameters.

Growing cannabis for medical use demands careful supervision of active ingredients such as tetrahydrocannabinol or THC, which gives recreational users their high but is not recommended for all patients, particularly children.

"With the support of the (health) ministry, which has always had a pioneering attitude to this issue, we have built up expertise in clinical trials and we can share it with companies in the United States and Europe," said Gedo.

He cites initial results of trials on patients with Crohn's disease, which is characterized by chronic inflammation of the intestine, diarrhea and recurrent abdominal pain.

Forbidden to export its cannabis plants, Israel is concentrating instead on marketing its agronomic, medical and technological expertise in the hope of becoming a world hub in the field.

The prestigious Hebrew University of Jerusalem has just opened a cannabis research center joining 19 other teams from local academic institutions.

About 200 industry players gathered in Tel Aviv this month for Canna Tech, an international conference on the industry.

Suited salespeople, some a little red-eyed despite a ban on consumption laid down by the organizers, exhibited products including electronic cannabis cigarettes, cannabis-based creams and ointments and a remedy for dry mouth.

Some startups are focused on the plant's by-products, others on user accessories, but a few have bigger ideas.

"Look at what has happened in the past two years, the speed at which legalization of cannabis is advancing," said Saul Kaye, head of the first Israeli incubator for cannabis industry startups.

"We're not going to miss this opportunity, and seeing what the first investors are putting on the table, we feel that it is going to be very big."