Zubeen Garg had posted an emotional letter addressed to Sarbananda Sonowal on social media.

Highlights Zubeen Garg was credited for the BJP's win in 2016 assembly elections

He has been vocal against the Citizenship (Amendment) Bill 2016

FIR after unverified audio clip of the singer criticising bill goes viral

Assamese singer Zubeen Garg, whose campaign song was credited for the BJP's win in 2016 assembly elections, has been charged for allegedly making derogatory remarks on the Bharat Ratna amid protests against the Citizenship (Amendment) Bill 2016 in the state.

The FIR, filed after an audio clip went viral on social media, says the singer defamed the country's highest civilian award. It has not been verified if the voice in the audio clip is of Mr Garg.

Zubeen Garg has been vocal against the BJP over the controversial bill. Earlier this month, the singer demanded that the BJP return the votes it got through his election song during the 2016 elections.

Last week, Mr Garg released a new song against BJP and Citizenship (Amendment) bill. The song “Politics No koriba Bondho” ( Don't do politics my friend ) was an instant hit among youngsters.

On January 8, Mr Garg had threatened to protest if Chief Minister Sarbananda Sonowal failed to take steps to scrap the controversial Bill within seven days. The singer had posted an emotional letter addressed to Mr Sonowal on social media along with his photograph holding the letter.

"Even if the Citizenship Bill has been passed in the Lok Sabha, Sarbada (Sarbananda Sonowal) can say no to it. Speak and see, rest will be seen later. I am still keeping my cool. I won't be in Assam for one week. It will be good if Sarbada takes some action before my return. Otherwise this time, I will agitate on my own. What I will do, I don't know," he said.

While Zubeen Garg is yet to respond, police sources have indicated that they would investigative the allegations.