Mumbai Mayor Kishori Pednekar has received a death threat and is set to file a police complaint.
Last year too, Ms Pednekar, a Shiv Sena leader, had received a threat.
The Mayor has received a letter written in Marathi in which foul language has been used. The letter warns that if she messes with "Dada", there will be repercussions.
Officers from the Byculla police station in Mumbai have reached the Mayor's residence and have already launched an investigation into the matter.
Last year, Ms Pednekar had received a threat over the phone. The caller told her that he was calling from Jamnagar in Gujarat and threatened to kill her, she had told police.
The police had later arrested the accused from Gujarat.
The fresh threat comes amid the row over a BJP leader's alleged objectionable remark on Ms Pednekar.
The Maharashtra State Commission for Women has asked the Mumbai police commissioner to submit a factual report about the alleged remark by BJP leader Ashish Shelar in connection with the recent cylinder blast in Worli.
Taking to Twitter, the Commission's chairperson Rupali Chakankar said "insulting" comments made about women by responsible public representatives "will not be tolerated".
Ms Pednekar was elected unopposed as Mayor of the Brihanmumbai Municipal Corporation in November 2019. She and Deputy Mayor Suhas Waadkarand, also a Shiv Sena corporator, were elected unopposed as the BJP, Congress and National Congress Party (NCP) did not field candidates for the posts.
Later that year, the Sena parted ways with the BJP and formed the Maha Vikas Aghadi government with the Congress and the NCP.
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