Thousands of Indians converged on a ceremonial boulevard in the capital amid tight security to celebrate the Republic Day on Sunday, which marks the 1950 anniversary of the country's democratic constitution.

The pomp and pageantry came, however, as hundreds of thousands of people protested across the country against a citizenship law that many fear is discriminatory against the minority Muslim community.

Brazil's president Jair Bolsonaro was the chief guest of the annual Republic Day parade, aimed at showcasing India's military hardware and cultural diversity.

But like numerous parts of India, protesters also gathered in New Delhi, including in the area of Shaheen Bagh, where hundreds of residents have blocked a major highway since December in protest against the controversial Citizenship Amendment Act and the National Citizens Register (NRC).