Mumbai: A political row has erupted in Maharashtra after BJP minister Girish Mahajan described Operation Blue Star as a "black day", drawing sharp criticism from opposition parties, which have demanded his resignation.Mahajan, who represented the Maharashtra government at a commemoration event marking the anniversary of Operation Blue Star at the Damdami Taksal headquarters in Amritsar last week, said, "For us, Operation Blue Star is a black day. We cannot forget June 6, 1984, the way our brothers and sisters were martyred and killed. Our religious place was attacked. I will say that it was a military attack on our holy shrine. Indira ji forcibly sent them (the Army) to Punjab and into our sacred place, and in such a cruel manner our people were killed."The minister also compared Operation Blue Star with the attack on the Golden Temple by Afghan invader Ahmad Shah Abdali, triggering further controversy.