Here are the latest developments:
"Mahatma Gandhi gave us the message 'Quit India, Clean India'," the PM told a gathering of hundreds of students.
Mr Modi also invited nine people to join the cleanliness drive and requested each of them to draw nine more into the initiative to take it viral.
The PM then flagged off a walkathon at Rajpath as part of the campaign and even joined the participants, walking alongside them for some time before getting into his car.
Early this morning he visited Rajghat, the memorial to Mahatma Gandhi. From Rajghat, the PM headed to Valmiki Basti, a housing colony in the capital where sanitation workers live. Apart from offering prayers at a temple and visiting a house that Mahatma Gandhi lived in, Mr Modi swept the streets there in a symbolic start to the cleanliness drive.
He also made a surprise stop and inspection at the Mandir Marg Police station close by.
October 2, Mahatma Gandhi's birthday, is a public holiday usually, but this year the Prime Minister has ordered a full working day for government employees.
Mr Modi has ordered bureaucrats and ministers leading their departments in cleaning offices, including toilets, today. In recent days, ministers like Ravi Shankar Prasad, Smriti Irani and Ram Vilas Paswan have been seen sweeping parts of their offices.
Early this morning, Aam Aadmi Party leader Arvind Kejriwal was seen cleaning the streets near the Prime Minister's residence.
Mr Modi has stressed the importance of sanitation in almost all his public speeches since his May victory, vowing to make India clean by 2019, to coincide with the 150th birth anniversary of Mahatma Gandhi, who said, "sanitation was more important than independence."
Roughly half of India's population do not have toilets in their homes, a health and safety problem that Mr Modi has also vowed to fix. In a joint editorial written with the PM on Tuesday in the Washington Post, US President Barack Obama said that his country would help with the Clean India initiative.
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