Assam Chief Minister and BJP leader Himanta Biswa Sarma and Congress General Secretary Priyanka Gandhi Vadra have been served notices by the Election Commission over alleged poll code violations.
The Election Commission (EC) told both the leaders to reply to the notices by Monday evening.
The EC warned it will presume both leaders have nothing to say if they do not respond before the deadline ends, and will take "appropriate action" without contacting them again.
The Congress in its complaint to the EC alleged Mr Sarma in an election campaign speech targeted Chhattisgarh's only Muslim minister Mohammad Akbar last week. During his speech in Kawardha in Chhattisgarh on October 18, Mr Sarma allegedly took a controversial swipe at Mr Akbar.
In the complaint against Priyanka Gandhi, the Rajasthan BJP said she "made false statements" on Prime Minister Narendra Modi.
"It has been alleged that you have invoked the personal religious devotion of the Prime Minister. Further, it is averred that relation between an individual and a deity cannot be a matter of public scrutiny and your statement diminishes the devotee in the general estimation of the public," the EC said in the notice to Priyanka Gandhi.
The assembly elections in Rajasthan and Chhattisgarh are scheduled to be held next month.
While campaigning in Chhattisgarh, Mr Sarma had also attacked the Bhupesh Baghel-led Congress government over several issues, including religious conversion.
"Today, the tribals of Chhattisgarh, who are dear to us, are being encouraged to convert their religion on a daily basis. And when someone raises their voice against it, Bhupesh Baghel ji says 'we are secular'. Is beating up Hindus your secularism? This country is a country of the Hindus and will belong to Hindus. Do not teach us secularism, we do not need to learn secularism from you," Mr Sarma said.
The Congress in the complaint alleged Mr Sarma's remarks showed a clear-cut intention to incite sections of society against one another.
In the notice, the EC drew Mr Sarma's attention to a provision in the model code of conduct that says "no party or candidate shall include in any activity which may aggravate existing differences or create mutual hatred or cause tension between different castes and communities, religious or linguistic."
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