The evening turban-tying class in the Sikh-dominated Indian city of Amritsar is packed with pre-teen boys learning a centuries-old tradition -- that religious leaders fear is under threat.

Over the next 90 minutes, the instructors unfurl long strips of cloth in vibrant hues from indigo to burgundy, and proceed to knot, pleat and finally tie them carefully around the boys' heads.

The most visible symbol of Sikh pride and identity, the turban is an eight-metre (26-foot) piece of cloth, used by Sikh men to manage the long hair which their religion forbids them from cutting.

But in India, young Sikh men are increasingly putting fashion before tradition -- cutting their hair short and shunning the turban completely.

It has also been abandoned by many members of the sizeable Sikh diaspora in countries like the United States, where Sikhs have been attacked over the mistaken belief that the turban marks them as Muslim extremists.

Such a motive has been suggested for the recent killings at a Sikh temple in the US state of Wisconsin where a gunman -- with alleged white supremacist links -- gunned down six worshippers.

Sikh boys are expected to tie and wear the turban by the time they reach adolescence, and 12-year-old Upneet Singh began attending the "turban clinic", as the classes in Amritsar are popularly known, about two weeks ago.

"I go to a religious school where the turban is compulsory at my age, so I come here to learn how to tie it," he says.

It is so important that observant Sikhs in the Indian military wear them instead of helmets even in frontline combat situations.

For religious leaders such as Avtar Singh, president of the trust that runs Sikhdom's holiest shrine, the Golden Temple in Amritsar, forsaking the turban is tantamount to a rejection of the Sikh way of life.

"The turban is the Sikh identity, it is a sign of our self-respect, our pride," the bearded 71-year-old told AFP at his offices near the temple.

"No Sikh is complete without his turban," insisted Singh, who blames increasing exposure to western influences for undermining religious traditions among India's 20 million-plus Sikhs.

"We live in a very westernised environment. And these days, Sikh parents don't teach their children enough about our history so they don't adopt our customs," he said.

-- Fashion or survival instinct? --

Shop worker Manjinder Singh cut his hair for the first time seven years ago, when he was 15.

"I cut it because it was more fashionable to keep it short. It's more modern," he said, as he sat down for a trim at a local barber's.

"My parents weren't pleased, but they just gave up trying to change my mind," he said.

If some Sikhs have willingly cast aside the turban for reasons of style, others have unwillingly done so out of a sense of self-preservation.

The assassination of Indian prime minister Indira Gandhi in 1984 by her Sikh bodyguards triggered an anti-Sikh pogrom that left thousands dead, and saw many Sikhs shave their beards and cut their hair to escape the violence.

Jaswinder Singh, who was 15 at the time of the riots, said the experience was a personal turning point that reinforced his faith.

"So many Sikhs died when I was young, it made me realise that I wanted to grow up and do something for my faith, for my community," he told AFP.

In 1997, when he began to notice young Sikhs frequenting hair salons, he knew he had found his cause, and in 2003 the Amritsar-based advocate established his "turban pride" movement, including regular tying clinics.

According to Singh, fewer than half of all Sikh youths in Punjab state wear turbans today, and he set up the clinic as part of a multi-pronged effort to bring them back into the religious fold.

Singh says his classes, held six days a week, are often full and have been a major success, paving the way for around 50 similar clinics to be set up by other Sikhs in Punjab.

-- Poems and beauty contests --

In addition, Singh organises turban-tying competitions, turban-themed poetry readings, and a beauty contest called "Mr Singh International" open only to Sikhs who don the headgear.

He also stages mass turban-tying ceremonies known as "dastar bandi", traditionally held to mark male Sikhs' coming of age.

Although the dastar bandi used to be a key event in every Sikh male's life, its popularity has waned as families have abandoned the tradition.

Under Singh's scheme, dozens of boys are initiated in monthly ceremonies during which priests and other religious figures tightly wrap turbans around their heads to the sounds of the congregation chanting.

In a bid to ensure that the boys do not shed the headgear for more exciting options as they get older, Singh has developed a computer programme -- Smart Turban 1.0 -- which showcases 60 different ways to tie a turban.

"If a Sikh youth loses the turban today, then maybe tomorrow he will abandon the religion all together, that is what I am afraid of," he said.

"That's why we need to save the turban. This is not just about the turban, it is about what it means to be a Sikh."

Singh said he sympathised with Sikhs living overseas who face the challenge of assimilation and feel that wearing the turban leaves them vulnerable to possible hate crimes.

"I understand why members of the Sikh diaspora would worry and think about giving up the turban, out of fear that they would be attacked, but I hope they don't do that.

"Historically, Sikhs have been attacked many times before and whenever we are attacked we unite and we become stronger, our faith becomes stronger," he said.