New Delhi, May 31: The Tamil Nadu government has filed a caveat before the Supreme Court in the Sterlite Copper unit shutdown plea case on Thursday. A caveat means a court cannot take any action in the case before hearing the side that has filed the caveat. Earlier this week, the state government had ordered a permanent shutdown of the unit following protests over the health hazards the unit posted. The shutdown came soon after the power supply to the unit was cut off on the directions of the Pollution Control Board. (Also read: NHRC Issues Notice to DGI Over Deaths in Police Firing) Also Read - Supreme Court Sets up National Task Force to Streamline Oxygen Allocation Across Country

The plant had been closed since March 27 for maintenance. In April,  the pollution board refused to renew its license to operate. The matter is sub judice and the next date of hearing is June 6, say media reports. Also Read - Central Vista Project: Supreme Court Dismisses Plea Seeking Halting Construction Work, Asks High Court to Pass Order

The latest protests, which drew national attention, began about three months ago but came to a head this month when agitators were not allowed to proceed towards the unit. In protest, they lobbed stones at police. Police then opened fire, leading to 13 deaths and injuries to several others. Questions were raised over the need to use assault rifles on protesters and the Home Ministry sought a report from the state government. A plea was filed seeking an independent NHRC probe. Also Read - Centre Has To Supply 700 Metric Tonnes Of Oxygen To Delhi Everyday Till Further Orders, Says Supreme Court

Meanwhile, the state government has handed over the probe to CBI. In another development, actor-turned-activist Rajnikanth visited Thoothukudi and promised Rs 2 lakh as compensation to the family of each of the victims. He also warned the people that if they resorted to agitation like this, the state would soon turn into a cemetery.

Another PIL filed by activist Fatima Babu has won a stay in the Madras High Court that stalls further expansion of the unit.