Seeking to turn the table on Kejriwal, the Congress leader said he would also be posing him questions tomorrow and asked Kejriwal whether he would dismiss like RSS, Anna Hazare and Ramdev the "uncomfortable" questions asked to them by him.
In a letter to Kejriwal, Singh said "when YP Singh (Retd IPS), your former colleague in civil society movement, called you a Hitler, I could see the streak in you.
"My opinion about you of a well-meaning crusader of public issues has now changed to a self-serving ambitious megalomaniac with scant regard for democracy," he said.
Digvijay Singh claimed Kejriwal couldn't get along with Aruna Roy, who was "your guru in RTI movement. Then you parted ways with Kiran Bedi and now, also with Anna whom you used as a front to give your ambitions a touch of respectability".
He claimed Kejriwal wanted him to recommend his name for being made a member of the National Advisory Council.
"You wanted to meet her (Sonia Gandhi) and had requested me to propose your name for inclusion in the NAC. I did propose your name but failed. She took Aruna Roy," Singh said.
He also said Kejriwal had first met him during a seminar at Berkeley University in San Francisco and that the Congress leader was quite impressed by his commitment to the cause of RTI.