The ceremony in the central city of Nagpur coincides with the 50th anniversary of conversion to Buddhism of Bhimrao Ramji Ambedkar, a low-caste Hindu and the founder of India’s democratic constitution who fought for the rights of the ‘untouchables’, or those at the bottom of the caste hierarchy.

‘This is not about religion or conversion. It is about a constitutional right, the right to practice one’s own religion,’ said Udit Raj, president of the Indian Justice Party.

Raj, a Dalit who converted to Buddhism in 2001, is the main force behind the conversion move in Nagpur which is in the western state of Maharashtra where there are no official curbs on religious conversions.

But in several states including neighbouring Gujarat and Madhya Pradesh, the ruling Hindu nationalist Bharatiya Janata Party has introduced or strengthened laws to stop what it says are forced conversions, mainly by Christian missionaries.

Under the new laws anyone planning to leave the Hindu fold, the country’s majority faith, must obtain certificates from officials and affidavits from courts, stating they were converting out of free will.

Dozens of riot policemen were deployed at a sprawling public park in Nagpur where the mass conversion was planned. Trucks packed with people planning to convert were seen entering the area.

More than 16 percent of India’s 1.1-billion population are ‘Dalits’ or formerly untouchables, who occupy the lowest rank in a 3,000-year-old Hindu caste system that has been dominated by the once-priestly class of Brahmins.

Converting to other religions has been seen by many Dalits as an escape from the rigid caste system.

Though caste discrimination is outlawed and the government has reserved quotas in educational institutions and government jobs for Dalits, they still face social discrimination in many parts of India and even violence from higher caste groups.

‘If someone feels empowered by practicing a different religion why should he be barred?,’ Raj said.

Hindu scriptures separate people into Brahmin priests, warriors, farmers and labourers and artisans, while the rest are beyond definition -- literally untouchables who perform the most ‘degrading’ jobs such as tanning of animal hides.

‘I’m here to convert to Buddhism because it is a religion that believes in equality and rejects social hierarchy,’ said Ramtej, a landless Dalit farmer who gave only one name.

Hindus form 80 percent of secular India’s billion-plus population while Muslims account for over 13 percent, Christians less than three percent and religious minorities such as Sikhs, Buddhists, Jains and Parsis make up the rest.