Kejriwal, who has been attacking Dikshit on the issue of hike in power tariff, has been given two days' time to tender an "unconditional public apology", failing which a defamation suit will be filed against him.
"He (Kejriwal) has been given two days to apologise. If he does not apologise, then a defamation suit will be filed against him," Dikshit said when asked about the notice served on the activist by Khera.
In the notice, Khera charged Kejriwal with making "derogatory" remarks against the Chief Minister.
"Immediately withdraw all the allegations and aspersions made by you against Sheila Dikshit, the Chief Minister of Delhi, which has thus defamed my client and the office of the Chief Minister of Delhi, in a talk show at least on three prominent channels and newspapers in equal, if not more prominence, than the original defamatory content.
"Tender an unconditional public apology to my client to her satisfaction through the print and the electronic media with regard to the said baseless allegations and aspersions and using foul and filthy language," the notice said.
Kejriwal, who plans to contest Delhi assembly polls next year, has been organising protests against power tariff hike in the city and accused the government of stalling Delhi Electricity Regulatory Commission's move to cut power tariff by 23 per cent in 2010.