"A woman residing in suburban Bandra had intimated deputy commissioner of police (Zone 8 and 9) on August 9 through a letter that she has got credible information that some anti-social elements would indulge in violence (during the protest)," state BJP spokesperson Madhav Bhandari said at a press conference.
He showed the letter, written in Marathi, to the media persons, but declined to reveal the identity of the woman.
The letter says members from the Salim Lightwala gang were planning large-scale violence at the venue, to drive home the point that the riots -- in which two persons were killed and several others, mostly policemen and media persons, were injured -- was a planned act, Bhandari said.
The August 11 protest was organised by Raza Academy and some other groups to denounce alleged atrocities on the minority community in Assam and Myanmar.
The BJP leader also displayed a photograph, which shows Maulana Moin Miyan, a member of Raza Academy, with Home Minister R R Patil and Minister of State for Housing Sachin Ahir (both belong to the Nationalist Congress Party) at an iftar party.
"The government is responsible for the violence. They had information about it two days prior to the incident. The person in the photograph with Patil is one of the accused in the violence," Bhandari added.