Delhi Chief Minister Arvind Kejriwal has committed a "serious act of libel" through his "malicious falsehood by alleging that my wife and daughter are linked to fake companies", Union Finance Minister Arun Jaitley told the Delhi High Court on Tuesday.

Jaitley was being cross-examined by Kejriwal's counsel and senior advocate Ram Jethmalani in connection with the Delhi and District Cricket Association (DDCA) defamation case filed by the union minister against the Delhi Chief Minister and five other Aam Aadmi Party (AAP) leaders.

Responding to Jethmalani's queries in the court of Joint Registrar Amit Kumar, Jaitley said that allegations were not only false but Kejriwal also took the public discourse to a "very low level" and made "highly defamatory" allegations of corruption, which has "seriously damaged my reputation".

The union minister said many people in social media make irresponsible statements about people in public life but "when a Chief Minister endorses them, it becomes a grave and serious matter".

"Even false allegations gain credibility. Repetition of libellous statement gives me a cause of action against the person particularly if he has a stature, to take action against the said person," Jaitley explained why he decided to sue Kejriwal and not the others who had targeted him.

Jaitley explained his stance of filing case against Kejriwal after Jethmalani asked him why did he not sue Madhu Kishwar (a social activist), who tweeted about the alleged corruption by the minister in DDCA, and instead sued Kejriwal, who allegedly re-tweeted Kishwar's tweet.

"The repetition by a Chief Minister adds greater credibility to the falsehood contained in the tweet," Jaitley added.

Jethmalani, who was expelled from the Bhartiya Janata Party (BJP) in 2013, targeted the Finance Minister by asking various questions relating to his political career.

The lawyer even asked Jaitley if he was aware that he advised Narendra Modi not to set him up as a BJP candidate from Amritsar constituency for 2014 Lok Sabha election. The Joint Registrar, however, disallowed the question, saying it was irrelevant to the case.

Jethmalani also reminded Jaitley that he lost the 2014 Lok Sabha election from Amritsar by more than 1 lakh votes. "Was it the first time you put your great reputation at test in a democratic manner?" said Jethmalani.

An election result is the outcome of "several factors prevailing in the constituency and not merely a test of a candidate's reputation", Jaitley said, reminding Jethmalani that Kejriwal lost by 3.5 lakh votes.

Jaitley was also asked if he had any personal enmity towards former cricketer Bishan Singh Bedi, who had made several allegations of corruption against him.

To this, minister replied: "I have no personal enmity with him. I do remember that he once contested the DDCA President post and lost it... I continued to maintain the due courtesies that he deserved as an eminent cricketer. He also campaigned against me actively in the Lok Sabha elections."

Jaitley was also questioned by Jethmalani whether Prime Minister Narendra Modi had known that he was suing Kejriwal.

In December 2015, Jaitley filed a civil defamation case against Kejriwal and AAP leaders Kumar Vishwas, Ashutosh, Sanjay Singh, Raghav Chadha and Deepak Bajpayee, claiming that they made "false and defamatory" statements in the case involving DDCA, thereby harming his reputation.

He had claimed that the AAP leaders attacked him over alleged irregularities and financial bungling in Delhi's cricket association, of which he was the President for about 13 years.

The cross-examination would continue on May 15 and 17.