Posing as customers, three men entered a little New Delhi workshop, pulled out a gun, and demanded the most valuable thing there — hair.

Key points: The robbers left a wig-maker deep in debt

The robbers left a wig-maker deep in debt Hair is big business in India, with wigs and hair extensions exported around the world

Hair is big business in India, with wigs and hair extensions exported around the world The town of Tirupati collects hundreds of tons of hair every year

They fled half an hour later with 200 kilograms of wigs and raw hair worth more than $US20,000 ($27,157), police said on Thursday.

The men left behind a wig-maker deep in debt.

"People think wigs are cheap but they cost a fortune to make," Jahangir Hussain told The Indian Express newspaper after the robbery last Friday.

He said he had borrowed more than $US17,000 ($23,000) to buy hair last month from South Indian wholesalers.

"We breathe life into dead hair," Mr Hussain, who proudly says his wigs can last a decade if they are cared for properly, said.

Hair is big business in India, estimated to bring in more than $US300 million ($407 million) a year, with wigs and hair extensions exported around the world.

Much of the hair is collected at Hindu temples in South India where devotees have their heads shaved as a form of religious sacrifice.

The best-known temple for tonsuring — as the practice is known — in the town of Tirupati collects hundreds of tons of hair every year, auctioning it off for millions of dollars.

AP