Current charedi trends encourage boys to leave behind their secular education as young as possible in order to advance to full-time Talmudic study in yeshivot.

But not every young teenager is cut out for such intensive study and an increasing number fall by the wayside, indulging in just those aspects of secular society from which their elders tried in vain to protect them.

Rabbi Klein, who was not born into a religiously observant family, has come up with an Israeli institution which combines individually designed Jewish educational programmes with secular studies, as well as character-training welfare and craft work and exciting adventure trips.

His boot-camp style yeshiva was modelled on American Jewish summer wilderness adventure programmes designed for problem yeshiva students.

He said: "In the USA, kids coming from religious homes who were leaving the fold for various reasons did wonderfully if they went to these camps.

"But as soon as they came back to their environment and negative friends, they slipped back.

"We reckoned that the answer was to have an adventure programme all the year round instead of just two months a year."

Rabbi Klein described the programme as "a taste of boot camp, but not too tough".

He continued: "All over the world, no matter what colour kippa they wear, for various reasons a minority of 5-10 per cent of religious boys don't fit in and fall between the cracks. That's where the danger is.

"Instead of pretending that the kids are learning all day and they're not, we give them positive things to do, including learning and self-esteem building activities."

An ACE day is divided into three.

Boys, who normally would sleep all morning and stay up all night, have to be up at 7.30am and in bed by 11pm. But because the programme is so excitingly geared to their needs, they don't complain.

Rabbi Klein said: "We've had kids who love school so much they don't want to go home for the holidays and are willing do things they normally would never do, like studying."

The students, whose only dress code is that they must cover their heads and not wear T-shirts with unsuitable words, have to put on tephillin in the morning and participate in some part of mincha and maariv.

The day begins with the religious curriculum which is aimed at encouraging the individual pupil to have a "close relationship with Hashem, love for learning, understanding of Judaism and inspiration".

Rabbi Klein says: "Interactive work helps pupils overcome past problems so that they can enjoy it. Even those who don't, love the rest of programme so much that they are ready and willing to participate."

Religious studies are followed by a secular curriculum leading to an American GED high school graduation diploma, which is also recognised in England and Israel.

From 3.30pm, boys engage in various chessed activities from hospital visiting, singing to sick people to repairing and making things for the poor and widows.

Rabbi Klein said: "Our boys built a swinging bench and brought it to the house of the Itamar family whose members were recently killed."

Twice a week the boys learn wood and concrete work.

Rabbi Klein said: "They make their own beds, desks and benches. Then they take pride in them."

One whole day a week pupils go on a wilderness adventure which could include a 10-hour hike or snorkelling. Based on a moshav near Bet Shemesh, the boys tour the whole country from Eilat to the Golan.

Rabbi Klein said: "The moshav members love the boys. But there is not much interaction because they are older and Israeli.

"The surroundings are very pastoral and quiet, far away from the centres of trouble for these kids. They can't go to town when they want."

He continued: "The wilderness adventures are not just holiday trips. We are not babysitting the boys. The intent is to build up their self-esteem.

"If they have literally scaled a mountain, when they look down they feel so incredible. It could be the first time in their life that they are feeling good about themselves because they have accomplished something.

"They also conquer fears when they jump off 10-metre bridges into water."

He denied that the boys had to be as strong as Arnold Schwarzenegger, just ready to participate.

ACE has just completed its second year, starting with six boys aged 16 or over, rising to 16 last year. Registration for the next academic year has so far doubled the level at this time last year.

Students from the USA and the UK, as well as Israeli boys from Anglo backgrounds, mainly stay for a two-year programme.

Rabbi Klein said: "Every kid has grown tremendously in his own way. We have had a 95 per cent success rate.

"The Jewish world should be duplicating what we are doing and there should be 10 schools like ours."

However, because of its high student staff ratio and its range of services including a school psychologist, ACE is very expensive to run.

So Rabbi Klein has now set about fundraising to build an endowment fund for those who can't afford the steep fees.

New York-born Rabbi Klein was initially drawn to Judaism by his love of Israel.

His father had become religious before he did.

He said: "My father, although not originally observant, was always a very spiritual person. It just clicked when he saw the beauty of Judaism. It just flowed and connected."

Rabbi Klein first went to Israel with the National Conference of Synagogue Youth when he was 16 and fell in love with the country. The following year he went again with a friend.

Studying at Arizona University, he opted to spend six months at Tel Aviv University.

He said: "I felt Israel was where every Jew should live, not initially from a religious angle, even though like my father I was very spiritual.

"As a kid, I always believed in God. When I got back to college I started to read more, especially about Israel, as well as more religious stuff.

"I decided I wanted to move to Israel right after graduation in 1990."

Once in Israel, he said: "I became religious pretty quickly, but not overnight."

For his first few years in Israel, Rabbi Klein worked as an OU outreach worker with the homeless and those with psychological problems.

After studying at Jerusalem's Boston Kollel, Rabbi Klein taught English for two years in a Ministry of Education high school.

Married to his French-born wife Odelia, he returned to the USA in 1998 during which time his father was tragically killed in a plane crash over Nova Scotia.

He said: "I got stuck there for seven years, studying and working as a campus rabbi. We moved back in 2005."

Back in Israel, he taught in a local yeshiva, before doing campus outreach work with American students at Israeli universities for Ohr Sameach - work he still does part-time.

Details of ACE on www.aceisrael.com