With thousands shouting "Bharat Mata Ki Jai", singing a tuneful "Lokpal, Lokpal" and devotional songs as well as waving placards at Rajghat, Hazare got on to a raised platform and went on a hunger strike, his second in two months.
In a hard hitting speech, his associate Arvind Kejriwal accused the Congress as well as other political parties of ruining the nation and said civil society now wanted a systemic change.
"We are not here to change the government, we want to change the system," he thundered, speaking mostly in Hindi, to the cheers of the large crowds.
He said the government had tried to browbeat Hazare and his team by demanding various financial details including their personal incomes and their expenditure on various protest campaigns.
"Today we ask the Congress to put on the website all their income and expenditure of the past six decades," he said.
Former top cop and activist Kiran Bedi said: "We need a stronger law against corruption which can be trusted. The system should be approachable. We will consider ourselves free only when India is free from corruption. It is a second war of independence."
Listening intently were hundreds of supporters at Rajghat, the memorial to Mahatma Gandhi, as the tricolour fluttered behind Hazare.
They had started thronging as early as 7 a.m. although the fast was not to begin before 10 a.m. There was also a heavy police presence at the site. The fast will go on till 6 p.m.
One of the first to reach the venue was Kuldeep Singh of the Bhrashtachar Virodhi Party who came with his friends from Punjab.
"We have come here to support Anna. What the government did at the Ramlila ground was wrong and it should not have taken such a step. Corruption is a big issue and we have the right to protest against it," Kuldeep Singh told IANS.
"Anna and Baba Ramdev should come together and fight this battle together," he added.
In April, Hazare's five-day fast drew widespread support across the country and forced the government to set up a joint panel to draft a Lokpal bill to combat corruption in high places.
Vaibhav Kumar, one of the many young supporters of Anna, said: "Just like Gandhiji took the path of non-violence, Anna Hazare is doing the same and we are supporting that."
The people also referred to the police crackdown on Ramdev post midnight Saturday.
"What happened there is shameful. The people who gathered there were protesting peacefully. If the government can baton-charge peaceful protestors, then they should remove Gandhiji's photo from all government offices and the currency notes as well," he added.
Wearing a Nehru cap, another young Anna supporter said: "We are not aligned to any political party. Our only aim is to fight corruption."
Earlier in the day, before proceeding towards the fast site, Anna Hazare said: "The government action at Ramlila ground was an attack on democracy."
