More than 250,000 animals are being lined up for slaughter as Nepal embarks on a two-day religious festival where buffalo, birds and goats are sacrificed to appease a Hindu goddess.

Millions of Hindus flock to the ceremony, which is held every five years at the temple of Gadhimai, the goddess of power, in Bariyarpur, Nepal, near the Indian border.

The last time the festival was held, in 2009, more than 250,000 animals were killed, according to animal rights organisation PETA, who is campaigning to put a stop to the practice. 

The festival is 'kicked off' with the ritual slaughter of five thousand buffalo in a field near the temple, after which two days of ritual animal slaughter takes place. 

Animal rights activists such as PETA are campaigning to halt the mass animal-slaughter, but despite their efforts, the organisers of the festival has promised that this year will be the biggest yet. 

About 2.5 million devotees  have turned out for the festival, according to local government official Yogendra Prasad Dulal, who said it was 'impossible to estimate' the total number of animals sacrificed so far.

'It has been a grand day,' Mangal Chaudhary, head priest at a the Gadhimai temple said. 'The buffalo sacrifice has ended, but we will continue the rituals with goats and other animals for one more day,'

On the first day, worshippers slaughtered more than 6,000 buffaloes, which were coralled into holding pens in the fields, along with at least 100,000 goats and other animals, Chaudhary said.

The festivities will continue on Saturday when at least another 100,000 animals will die in the name of goddess Gadhimai.