Readers may find images in this article distressing.

Hindu devotees in Nepal have begun slaughtering hundreds of thousands of animals and birds in a ritual sacrifice for the 'Gadhimai Mela' festival.

The ceremony, which takes place every five years, is believed by worshippers to appease the Hindu goddess of power, in turn bringing luck and prosperity.

It is thought to be the largest such animal sacrifice in the world and has long attracted criticism from animal rights activists.

A butcher swings his blade to sacrifice a buffalo Credit: Reuters

"It is a ritual connected with people's faith," said Yogendra Dulal, an assistant administrator of the Bara district, near the border with India, where the temple is located. "We can't hurt their sentiments and ban the practice."

Tens of thousands of people attend the two-day ceremony, where around 500,000 animals are killed, according to estimates by Humane Society International.

A butcher holding his blade stands among sacrificed buffalo Credit: Reuters

Sacrifices begin at dawn when a rat, a goat, a rooster, a pig and a pigeon are killed.

Around 5,000 buffaloes are beheaded by butchers using swords and large curved knives.

The animal's heads are then buried in a huge pit, while the hides and skin are sold to traders.

It is not proper to kill animals in the name of religion. Uttam Kafle, of rights group Animal Nepal

India's Supreme Court recently asked the government to stopthe illegal movement of animals into Nepal for the ceremony.

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