Temple hair, which are offered by thousands of Indian women and a few men every day as a gift to Lord Venkateswara - the presiding deity, has already found its way to hundreds of British salons where it is sold in the form of real hair extensions costing up to 3,000 pounds a time.

The Hindu temple of Tirumala Venkateswara on the coastal state of Andhra Pradesh where, Hindu devotes offer their hair, is is also the starting place and principal provider for an astonishing industry, one that has seduced celebrities in Europe and America, and those rich enough to follow them. The trade in human hair is booming.

One leading manufacturer boasts that horde of celebrities, including Mischa Barton, Eva Longoria and Frankie Sandford of The Saturdays, have used its products. Fans of extensions, the appeal of human hair is obvious - it both looks and feels better than the synthetic additions made famous by stars such as Jordan and Britney Spears.

Moreover, the quality of Indian hair, which is strong and has for the most part never been subjected to Western shampoos, is known to be unusually good.

It is safe to say that the temple makes millions from the piles of thick black locks. Yet the women who once possessed the hair - many of them peasants - receive not a penny, donating their hair, instead, as a religious sacrifice.

The shaving ceremony and the sale of hair is not limited to this one holy site, but Tirumala Venkateswara attracts tens of thousands of pilgrims in a single day and is by far the dominant temple in the trade.

There are 18 shaving halls, all of them vast, and so big are the crowds that women and young girls can wait in the queue for up to five hours.

650 barbers sit in lines on concrete floor, deftly tying up into ponytails the hair of women seated in front of them. Small children being carried by their mothers can be heard whimpering. They too are candidates for tonsuring - the shaving of the head as a sign of religious devotion.

With a few expert sweeps of a razor, each head is shaved smooth and is then doused with water, washing away any blood caused by nicks from the razor. The average woman's head yields about 10oz of hair, which is worth about 210 pounds

Most of the women seemed stunned, their hands patting at a scalp that minutes before had been covered in glossylocks. Then in a flash they are ushered away and the next candidate sits down.

Often, as they wait for their turn, the women's faces are impassive, their lips pressed shut, as though trying not to cry.

"For poor rural women, their hair is their only vanity. They have saved up to make a once-in-a-lifetime journey. Thousands have made an oath to their gods - they may have asked to be blessed with a child or for a good harvest," the Daily Mail quoted Mayoor Balsara, chief executive of India's largest exporter of human hair, Sona Devi Trading Company, as saying.

"Should their wish be fulfilled, they offer their most precious possession as a sign of gratitude," Balsara said.

It is not just rural women who offer their hair to Hindu gods. The trend has been customised for well-educated, professional women from cities too. Instead of submitting to a full tonsure, they can donate a mere three strands to the temple.

Baskets filled with hair are collected every six hours and stored in a vast warehouse where it is piled knee deep. The hair, strong and healthy, has never been dyed or subjected to anything more abrasive than coconut oil and herbal soap.

Sometimes it has never been cut. The temple then auctions off the hair - even taking online bids - to exporters around the globe.

Mayoor Balsara transports the hair in fibre sacks by truck to Bengaluru, 150 miles away.

"We buy hair in metric tons.A ton represents 3,000 women," Balsara said.

Balsara buys about 50 tons a year and ships it round the world. India exports an estimated 2,000 tons a year. The best - or longest - hair will fetch at least 350 pounds per pound.

In his factories the hair is washed by hand in giant baths. Then the hair is laboriously pulled through long beds of spikes by hand to smooth it before being tied into neat bundles of 200 strands each.

The hair is then carefully packed into cardboard boxes and flown to Nepi in Italy where the pigment is removed, a process that sees the hair soaked in rows of small white baths for up to 20 days.

Great Lengths International, a leading manufacturer, supplies 1,300 salons in Britain alone, selling its products as 'ethical hair extensions' - ethical because the source of the hair is known.

After the bundles of hair have been coloured, polymer bonds, which mimic the molecular structure of real hair, are attached to them. The bonds will be used to fix the strands to the customer's head.

"'There are no official global statistics but it's fair to say that hair has become a commodity as precious as gold, diamonds or oil. Some top salons order up to 100,000 pounds worth of hair a year," Philip Sharp, UK managing director of Great Lengths, said.

The company said that European hair is too thin in diameter for the process; Chinese hair, meanwhile, is too thick and rigid for use with European clients.

In India, temple hair has been sold for centuries - mostly to stuff mattresses, or for the chemicals it contains. Temple officials argue that, unless they sell the hair, they would simply dispose of it.

The profit from the hair collected at the temples, an estimated 70 million pounds a year, is spent on orphanages and hospitals.