Kathmandu, July 28 (Reuters): A temple in southern Nepal known for the mass slaughter of animals at a festival there every five years has indefinitely banned animal sacrifice, India's Humane Society International said today.

The twice-in-a-decade ritual of slaughtering tens of thousands of animals at the Gadhimai temple, located about 145km south of Kathmandu, has drawn international condemnation from animal rights groups in recent years.

"Obviously we are very happy with this decision," said Manoj Gautam of Animal Welfare Network Nepal, which has been campaigning for an end to the slaughter.

"But it doesn't mean our job is done ... We need public support and participation to make sure this ban is upheld," he said. Temple officials were not immediately available for comment.

Millions of pilgrims from India and Nepal regularly attend the festival, where animals have been sacrificed in past years to Gadhimai, a goddess of power.

According to the Humane Society International, an estimated 500,000 buffaloes, goats, chickens and other animals were killed at the temple in 2009.

Those numbers dropped during the previous festival in 2014, after India's Supreme Court issued an order prohibiting animals from being taken across the border to Nepal for sacrifice at the festival, campaigners said.

Animal rights groups plan to spend the remaining three-plus years before the next festival working in Indian states that border Nepal to spread awareness of the temple's decision. Nepal's lawmakers are currently in the late stages of preparing a Constitution for the country.