MUMBAI: Hundreds of thousands of low-caste Indians lined up on Wednesday to bow before a memorial to a champion of their rights who died 50 years ago, as security officials kept a vigil to prevent any violence.

At least 800,000 low-caste Hindus, known as Dalits or untouchables, arrived in Mumbai to pay homage to Bhim Rao Ambedkar in the central Dadar neighborhood where he was cremated on Dec. 6, 1956.

Although the turnout was not surprising -- people congregate in similarly large numbers every year -- authourities tightened security around the city because of last week's violent demonstrations by low-caste groups across Maharashtra state, of which Mumbai is the capital.

The demonstrations were against the desecration of a statue of Ambedkar in northern India.

Ambedkar, himself a dalit and a prominent Indian freedom fighter, was the chief architect of the Indian Constitution, which outlawed discrimination based on caste.

Schools and colleges were shut on Tuesday and police with sniffer dogs patrolled streets in central Mumbai to maintain law and order.

''This security is a precautionary measure. We called in extra forces basically because of recent incidents and violence,'' said Mumbai police chief A.N. Roy.

''We are being cautious since there are so many people coming to the city. We want to ensure a smooth flow.''

Throughout the day, crowds of people placed flowers and garlands on Ambedkar's shrine in Mumbai's Dadar neighbourhood. Buddhist monks in orange robes also recited prayers in front of a small statue of Ambedkar, who had renounced Hinduism for Buddhism since he believed it treated people equally.

''People only remember Dalits on Ambedkar's birth or death anniversary. We are poor and will remain poor,'' said Shakun Pala, a labourer.

Pala said education, which could open the door to a better life, was available for only a few Dalits. ''I want my children to study, but it makes more sense to put them to work. It's better to feed the family than keep them in school,'' Pala said.

During last week's state-wide demonstrations against damage to a statue of Ambedkar, at least two people died when police fired into a crowd of protesters. Some 40 people were injured in separate clashes.—AP