Hindu temple officials herded thousands of animals into pens in a remote corner of Nepal in final preparations for a mass slaughter Friday, defying a growing chorus of protests.

Sword-wielding Hindu devotees were expected to turn the village of Bariyapur near the Indian border into the world's largest abattoir for the two-day religious festival.

Worshippers were gathering in the village for the Gadhimai festival which occurs every five years, ignoring animal rights activists who were holding a protest nearby against the slaughter.

"We are ready for the festival, everyone is in a celebratory mood," said head priest Mangal Chaudhary at the slaughter site.

Buffaloes were being coralled in holding pens for the festival devoted to Hindu goddess of power, Gadhimai, that sees hundreds of thousands of animals ranging from goats to rats butchered.

The festival kicked off at midnight amid tight security, with the ceremonial killing of a goat, rat, chicken, pig and a pigeon, before the mass slaughter on Friday.

Worshippers from Nepal and neighbouring India have spent days offering prayers to the goddess at a temple decked with flowers in preparation.

Some 1,200 police personnel were patrolling the village and surrounding area, to control crowds and avert possible clashes between worshippers and activists.

Authorities have also banned the sale of alcohol during the festival, according to local police official Lokendra Malla.

"It is a security issue, people get intoxicated and fight. We don't want any of that," Malla told AFP.

Although India's Supreme Court banned buffalo exports to Bariyapur, sparking initial fears of a shortage of animals, temple authorities told AFP all preparations were in place.

An estimated 300,000 animals had their heads chopped off or throats slit during the last festival in 2009, making it the world's biggest sacrifice of animals at any one site.

The spectacle leaves pools of blood across the temple grounds, the air thick with the stench of raw meat, while authorities dump buffaloes' heads into a freshly dug large pit.

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The goat and chicken flesh is distributed to devotees and villagers, while contractors bid to buy the buffalo and animal hides.

Animal rights activists accused temple authorities of "cashing in on people's beliefs".

"They are extorting money... in the name of entry fees, parking, and so on," said Manoj Gautam, president of Animal Welfare Network Nepal, who is in Bariyapur to protest the ritual.

According to legend, the first sacrifices in Bariyapur were conducted several centuries ago when Gadhimai appeared to a prisoner in a dream and asked him to establish a temple to her.

When he awoke, his shackles had fallen open and he was able to leave the prison and build the temple, where he sacrificed animals to give thanks.

A campaign to ban the festival has attracted support from celebrities including British actress Joanna Lumley and French movie legend Brigitte Bardot, who has petitioned Nepal's president to end the "cruel tradition".