Every five years a temple in southern Nepal plays host to an extraordinary religious festival in which hundreds of thousands of animals are sacrificed to the Hindu goddess of power Gadhimai.

For two days, the tiny village of Bariyapur near Nepal's border with India flows with blood as thousands of Hindu devotees flock to the temple to take part in what organisers believe is the world's biggest ritual slaughter.

Many travel from neighbouring India for the festival, which has been running uninterrupted for around three centuries and is due to take place on November 24 and 25.

But this year, a group of animal rights activists is campaigning to stop what it says is senseless cruelty to innocent creatures -- pitting themselves against Hindu devotees in this deeply religious nation.

"We launched our campaign to put a stop to the gruesome killing of animals in the name of God," said Pramada Shah, director of campaign group Animal Nepal which has launched an online petition demanding the festival be cancelled.

"Even in the 21st century, innocent animals are facing cruel treatment due to people's superstition."

The campaign received a local boost when it won the support of Ram Bahadur Bomjam, a young Nepalese man believed by followers to be a reincarnation of Buddha after supporters said he could survive without water, food or sleep.

Bomjam, dubbed "Buddha Boy" by Nepalese media, has spent the past year meditating in the jungle near Bariyapur, but last week broke his silence to condemn the festival.