BARIYAPUR, Nov 24, 2009 (AFP) - Up to a million Hindu devotees gathered Tuesday in a tiny village in Nepal to witness the slaughter of hundreds of thousands of animals in a mass sacrifice that has drawn widespread criticism.

Worshippers travelled long distances, many coming from neighbouring India, to attend the Gadhimai festival, which honours the Hindu goddess of power and takes place once every five years in southern Nepal.

A huge cry of "Long Live Gadhimai!" went up after the village temple's head priest launched the event with the ritual sacrifice of two wild rats, two pigeons, a rooster, a lamb and a pig.

The gathered crowd then rushed to a nearby field where 250 sword-wielding butchers were waiting to begin the mass slaughter of around 20,000 buffalo, brought by devotees to be sacrificed near the holy temple.

"This is a very special day for Hindu devotees," head priest Mangal Chaudhary Tharu told AFP as the Gadhimai festival began.

"All the people who came here to worship Gadhimai have been waiting a long time for this day. I am very proud to be part of this event," added Tharu, the fourth generation of his family to serve as a priest at the temple.

An AFP reporter at the scene said up to a million devotees were crammed into the area for the festival, many of them from India, where many states have banned animal slaughter for religious purposes.

Nepal's government has refused to put a stop to what it says is a centuries-old religious tradition, despite a vocal opposition campaign from local animal rights activists who say the slaughter is needless cruelty.

Their cause is supported by the well-known Indian animal rights activist Maneka Gandhi and by the French film star turned campaigner Brigitte Bardot, who this month wrote to Nepal's president urging him to put a stop to the festival.

Armed police have been deployed around the temple grounds and authorities have banned alcohol during the festival. The AFP reporter said the event began peacefully.