In a note to the minister today, Mr Kejriwal admitted to "making unverified allegations" and added, "I have nothing personal against you. I regret the same. Let us put the incident behind us and bring the court proceedings to a closure." After the apology, they both submitted a joint application asking to withdraw the defamation case filed by Mr Gadkari.
A similar letter to Kapil Sibal and his son Amit Sibal refers to comments made by the Aam Aadmi Party (AAP) chief in 2013 and says "the allegations made against you and father were unfounded".
Sources say the Delhi chief minister intends to get rid of all 33 defamation cases against him through similar out of court settlements and individual "understandings". The cases have been a drain on the party's money and resources, say AAP leaders, who are also keeping an eye on public response.

Among those on Arvind Kejriwal's "sorry" list is Finance Minister Arun Jaitley
As he tries to untangle himself from a mess of defamation suits, Mr Kejriwal is already in trouble with a section of his party for apologising to Bikram Majithia, a Shiromani Akali Dal leader and former Punjab minister. Mr Majithia had filed a criminal defamation case in 2016 against Mr Kejriwal and two other AAP leaders for targeting him over the problem of drugs in Punjab.
"I hereby withdraw all my statements and allegations made against you and apologise for the same," Mr Kejriwal wrote to him last week.
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Upset by the capitulation, AAP lawmaker Bhagwant Mann quit as the party's Punjab unit chief and Aman Arora resigned as his deputy.Perhaps the biggest challenge on Mr Kejriwal's "sorry" list is Finance Minister Arun Jaitley, who sued the AAP chief over allegations that he presided over corruption as chief of Delhi's cricket board DDCA. Mr Jaitley went personally to court to file the case, along with three union ministers as witnesses. He also asked for Rs 10 crore to compensate for what he called defamatory allegations.