Several retired judges, journalists, former diplomats, academicians and students launched the sit-in demonstration near the state assembly complex.
They were carrying placards with messages like "We are with Anna Hazare", "India Against corruption" "Join the fight against corruption" and "Go ahead Anna, we are with you".
The demonstrators also highlighted the need for a stronger anti-graft Lokpal Bill in the country.
"One of our members has began an indefinite fast from today (Thursday)," Rabi Das, president of civil society organisation Orissa Jana Sammilani (OJS), told IANS.
"From tomorrow (Friday), our members will also launch a relay fast until Hazare calls off his hunger strike," he said.
Anna Hazare's fast-unto-death, for the introduction of a stronger anti-graft Lokpal Bill, continued for the third day Thursday.
Hazare, who has named his fast the "second Satyagraha" on the lines of the movement launched by Mahatma Gandhi against the British rulers, has been joined by thousands of supporters all across the country and also abroad.
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