Delhi government spokesperson Nagender Sharma dismissed the allegations and said that Mishra had been given a "horribly wrong script".
Mishra posed nine questions to his friend-turned-foe Kejriwal including whether he was aware that a Russia trip of AAP leaders Sanjay Singh and Ashutosh "was sponsored by a man who is being probed for a Rs 400-crore high-security number plates scam".
Mishra also apologised to ex-AAP leaders Yogendra Yadav and Prashant Bhushan, who were expelled from AAP in April 2015 for "anti-party activities" after they questioned Kejriwal's leadership. They floated a new political party Swaraj India last year.
While reiterating that he will stay in the AAP to cleanse it, the rebel leader, who has been suspended from the party's primary membership, invited former India Against Corruption volunteers to help him make Delhi "corruption-free" and "Kejriwal-free".
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The former minister alleged that there was a scam of high-security number plates that came to the fore during the AAP government's first stint and is currently being probed by the Anti-Corruption Branch.
"Some of the companies that are being probed have a direct link with the person who funded their (Sanjay Singh and Ashutosh) trip," Mishra alleged.
Delhi government spokesperson Nagender Sharma rubbished Mishra's allegations in a series of tweets and said that Mishra had no clue of what he was talking about.
"Probe into High Security Number Plates scam was ordered by @Saurabh_MLAgk in 49 days govt in Feb 2014. Then LG Jung reversed the decision.
"In Jan 2016 Delhi government again sent the HSNP file to Delhi ACB despite LG having sent the case for arbitration on compnay's request," he posted on Twitter.
"Poor fellow has no clue of what he's speaking ! Who is misguiding him," he said.
The posts were retweeted by Ashutosh.
Mishra, who had trained his guns at Kejriwal soon after he was sacked from the ministry, had accused the Aam Aadmi Party chief of taking bribe. He had said that Kejriwal had opposed demonetisation as he allegedly had links with hawala operators.
He had been on a six-day fast to protest the AAP's "refusal" to disclose the details of the foreign trips of five party leaders.