Parliament building in New Delhi, India.

India's parliament has approved a long-awaited overhaul of the country's fragmented tax system to create a genuine single market in one of the most significant reforms to the Indian economy since liberalization began 25 years ago.

The bill, debated in New Delhi for almost a decade, will amend the constitution to permit replacing the current patchwork of national, state and local levies with a single, unified value added tax system.