NEW DELHI: India's president took the final step to create a powerful anti-graft watchdog on Wednesday, signing it into law two years after a mass anti-corruption movement swept the country and galvanised politicians into action.

Parliament saw rare unity last month when the ruling Congress and main opposition Bharatiya Janata Party (BJP) approved the bill creating a corruption ombudsman with sweeping powers to prosecute all politicians and civil servants.

President Pranab Mukherjee's final approval of the law comes as the world's largest democracy gears up for general elections due by May.

Voters have become increasingly incensed by a string of corruption scandals that have engulfed the nation.

Anti-graft hero Arvind Kejriwal, now Delhi chief minister, and his upstart Aam Aadmi (“Common Man”) party, whose mission is to clean up pervasive corruption and create a “bribe-free India”, trounced the Congress party in Delhi state polls last month.

Kejriwal, 45, was a key member of the grass-roots anti-corruption movement launched by 76-year-old social crusader Anna Hazare who demanded the tough law back in 2011.

Legislation was stalled by political bickering and debate about the extent of the bill's scope.

The Congress-led national government has been hit by a series of multi-billion-dollar graft scandals, from allegations of illegal distribution of cut-price telecom licences to the 2010 corruption-tainted Commonwealth Games.