Forget Louis Vuitton handbags or Prada suits – the latest must-have accessory for China’s wealthy elite comes not from the chic designer stores of Shanghai or Beijing but from the plains of Tibet.

The Tibetan mastiff, a rare, ancient and now extravagantly expensive breed of dog, has captivated those seeking to display their new-found affluence in a country experiencing a dizzying economic boom.

China has been in the grip of a fad for all things Tibetan since the opening last year of the world’s highest railway linking Beijing and Lhasa.

That has fuelled the soaring price of mastiffs, with a perfect specimen now fetching as much as £250,000 ($594,000) – up from just under £100 in the late 1990s.

These huge animals, weighing up to 113kg, are adapted to life in the thin air, freezing temperatures and wild mountains of Tibet, where they were domesticated 6000 years ago, and are regarded as the oldest, biggest and fiercest domestic dog.

Marco Polo described the mastiff as being as tall as a donkey and with a voice like a lion.

Traditionally, they have served as guard dogs for nomads who leave their tents all day to follow their flocks of yaks, sheep and goats.

Their bite is as fierce as their bark and visitors approach such tents with great caution.

But the scarcity and reputation for fearlessness, ferocity and faithfulness of the Tibetan mastiff have transformed them into a status symbol for China’s new very rich.

The mastiff may not only be the most expensive dog in the world, it is also among the rarest, with just 100 pure-bred animals believed to exist.

At the annual Yushu horse-racing festival on the border between Qinghai province and Tibet, several dozen mastiffs loll on the ground on Tibetan rugs, shaded by beach umbrellas from the blazing sun.

Ethnic Tibetan breeders display their finest dogs in the hope of finding a buyer among visiting Han Chinese tourists.

China’s nouveaux riches are willing to pay top dollar for a guard dog to protect their homes in the booming cities of China’s interior.

A puppy with a fine pedigree was on offer for about ¥30,000 ($4634) at Yushu.

However, prices have halved in the past year. It isn’t clear whether the fashion for the dogs is fading or whether demand has resulted in oversupply.