The man, who identified himself as Nachiketa Walnekar, a Bharatiya Janata Party (BJP) activist, created a ruckus at the packed press conference, but was then bundled away by Aam Aadmi Party (AAP) activists.
Kejriwal, who was sitting on the dais with other party leaders, got some drops of the ink on his face. But AAP national executive member Manish Sisodia's cap was smeared. Sisodia is contesting from Patparganj assembly seat. AAP membedr and senior lawyer Prashant Bhushan also had ink smudges on his hands.
Walnekar said he was a supporter of social activist Anna Hazare and was angry with the way Kejriwal disbanded the India Against Corruption movement, which was at the forefront of many campaigns.
"Anna Hazare never wanted the movement to end and Arvind Kejriwal has misused the name of Anna Hazare," Walnekar told media persons.
Reacting to the incident, AAP member Kumar Vishwash said: "It is an attempt to put our morale down."
BJP leader V.K. Malhotra said Kejriwal and his party members accuse the BJP for such incidents.
"They are the Congress's B-team. We don't approve of anybody throwing ink," he said.
Congress leader and Delhi minister Haroon Yusuf accused the AAP of seeking "publicity from such incidents".
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