Terming the political backlash against demonetisation as unfortunate, Prime Minister Narendra Modi on Sunday thanked the Indian diaspora for their support to the note ban to curb black money and fight corruption.

"I would like to thank you for supporting our fight against black money and corruption though political pundits called the note ban anti-people," Modi told about 1,800 overseas Indians at the 14th Pravasi Bharatiya Divas celebrations here.

Modi, on November 8, 2016, banned the old Rs 500 and Rs 1,000 notes to check black money, corruption, terror funding and counterfeiting of currency and gave the people 50 days till December 30 to exchange the phased out notes for new ones.

Ruing that the twin evils -- black money and corruption -- had adversely affected the country's economy and polity over the years, Modi said the time had come to eliminate them and help the honest people live with dignity and respect.

"I am grateful to all of you for supporting us in this war against the two evils that were weakening the country," the Prime Minister said.

The moment Modi raised the demonetisation issue during his 40-minute address -- in both English and Hindi, a majority of the audience cheered and applauded, hailing his decision.

"As corruption and black money were corroding our system from within, we had to take a strong stand and we did," Modi said.

Modi urged the diaspora, especially Non-Resident Indians (NRIs), to avail of the six-month extension given from January 1 to surrender the banned notes at designated Reserve Bank of India (RBI) offices till June 30.

"We have made arrangements at airports for NRIs to declare on arrival the old notes they are carrying and submit them to the RBI in exchange for new notes or crediting them to their bank accounts," he said.

The government has also given three months up to March 31, 2017, to Indians staying or travelling abroad to declare if they possess old notes.