"Arvind Kejriwal has been hurling unfounded allegations at me for the past three years despite the fact that not even a single case, neither serious nor minor, is lodged against me in any part of the country. I dare him to prove the charges within 15 days or be ready to be sued for libel," Nishank told reporters at a press conference in Dehradun.
He said he had sent two notices to Kejriwal in the past asking him to substantiate the charges of corruption levelled against him or offer a public apology but they went unresponded."If he dares ignore my threat this time he is sure to face a libel suit," Nishank said.
He wanted a probe into how much money the NGO run by Kejriwal had received from foreign countries and for what purposes.
Calling him an "opportunist", Nishank said a man whose party won 28 seats in Delhi solely by doing anti-Congress politics entered into an alliance with the same party to grab power.
"He made AAP the B team of Congress," he said. Nishank also accused Kejriwal of cheating Anna Hazare and moving away from the pre-poll promises made to the people of Delhi.