Ms Moitra had made a "pajamas" reference, which had sparked a controversy.
A case related to outraging the modesty of a woman has been registered against Trinamool Congress MP Mahua Moitra for a social media post on National Commission for Women chief Rekha Sharma.
Based on a complaint by Ms Sharma, the First Information Report was registered by the special cell of the Delhi Police on Sunday under Section 79 (word, gesture or act intended to insult modesty of woman) of the new criminal code, Bharatiya Nyaya Sanhita, which has replaced the Indian Penal Code.
Ms Sharma has also written to Lok Sabha Speaker Om Birla and requested him to take "appropriate action" against Ms Moitra.
The MP from West Bengal's Krishnanagar, who was disqualified from the Lok Sabha last year after the 'cash-for-query' row and was re-elected this year, had made a remark on Thursday in reaction to videos of the women's commission chief meeting women injured in the Hathras stampede in which 121 people were killed.
The videos showed someone holding up an umbrella for Ms Sharma and Ms Moitra had made a "pajamas" reference in a post on X, which had sparked a controversy. She later deleted the post and the police have sought details about it from the social media giant.
'Take Immediate Action'
The National Commission for Women (NCW) had taken cognisance of the remark on Friday and sought a case against Ms Moitra, but the Trinamool MP had remained combative.
Responding to a post by the NCW on X she had tagged the Delhi Police to take immediate action and arrest her, even telling them that she was in West Bengal's Nadia.
"Come on @DelhiPolice please take action immediately on these suo moto orders. Am in Nadia in case you need me in the next 3 days to make a quick arrest," Ms Moitra wrote, appending an "I Can Hold My Own Umbrella" dig against Ms Sharma at the end.
Posting earlier tweets by Ms Sharma in which the NCW chief appeared to call RJD chief Lalu Yadav and former Congress President Sonia Gandhi dumb and made a joke against Delhi Chief Minister Arvind Kejriwal with a "suhaag raat" reference, Ms Moitra also asked the Delhi Police take action against the "serial offender".
The Trinamool leader was expelled from the Lok Sabha in December last year based on an Ethics Committee report on the alleged 'cash-for-query' charges against her. She was accused of taking bribes, including Rs 2 crore in cash and "luxury gifts", from businessman Darshan Hiranandani for asking questions in Parliament that were critical of the Narendra Modi government. Agencies are also investigating that case.