The FIR against North Municipal Corporation of Delhi executive engineer Kapil Gupta was filed at Sultanpuri police station in outer Delhi on August 6.
Kumar, in his complaint, has accused Gupta of using "casteist word" against him and mentioning Dr B R Ambedkar in a "derogatory" manner during a sanitation inspection at H Block of Sultanpuri on July 27.
Kumar alleged that when he sought Gupta's reply on poor sanitation in the area, he allegedly used "objectionable words" against sanitation staff and when he objected to his language, saying he himself belonged to the Valmiki caste, the accused tried to manhandle him along with his 4-5 accomplices.
Retaliating to the allegations, the BJP-ruled North MCD house meeting yesterday authorised the municipal commissioner to file an FIR against Kumar for "misbehaving" with the civic body official.
An FIR has been registered on the complaint of Kumar and investigation is underway, a senior police officer said.
The BJP and AAP has been engaged in a bitter war of words on a range of issues from corruption to policing.