United Nations human rights experts have condemned the apparent excessive and disproportionate use of force by police against protesters calling for the closure of a copper smelting plant in Tamil Nadu over health and environmental concerns.

The plant is run by Sterlite Copper, a business unit of Vedanta Ltd., which is a subsidiary of the UK-based company, Vedanta Resources.

Police opened fire on thousands of protesters on 22 May, reportedly killing 12 people and injuring dozens of others marching against the expansion of the heavily polluting copper smelter in the southern port city of Thoothukudi.

The protest marked the 100th day of demonstrations against the copper smelting facility that had been proceeding peacefully. According to reports, protesters set fire to vehicles and threw stones at officers after being denied permission to march to the District Collectorate.

ÂWe are extremely concerned by the apparent disproportionate and excessive use of force, including the use of live ammunition, against protesters marching to raise legitimate human rights and environmental concernsÂ, the experts said.

ÂWe call on the Indian authorities to carry out an independent and transparent investigation, without delay, and to ensure that perpetrators of human rights violations be held accountable. The Government should uphold the rights to freedom of expression and assembly, as they are the cornerstone of democratic societies and a critical tool to identify and protect against business-related human rights abuses.Â

The experts noted that local and national judicial and administrative bodies have documented water contamination, air pollution and other forms of environmental degradation linked to the copper smelting plant and related activities.

ÂUnder the UN Guiding Principles on Business and Human Rights, all business enterprises have a responsibility to respect human rights, including identifying, preventing, mitigating and accounting for how they address their adverse human rights impacts, the experts said, calling on Sterlite Copper as well as its parent company, Vedanta Resources, to take immediate measures to mitigate pollution and to ensure access to safe water and health care.

ÂWe urge the Indian Government to take all the necessary measures to ensure that all business enterprises respect national as well as international human rights and environmental norms, and that the Sterlite CopperÂs smelting plant resumes operations only after meaningful consultation with affected communities and when fully complying with Indian environmental laws, a joint statement issued by the experts has said.

The signatories are: Ms Anita Ramasastry, Chair of UN Working Group on human rights and transnational corporations and other business enterprises, Mr Baskut Tuncak, Special Rapporteur on the implications for human rights of the environmentally sound management and disposal of hazardous substances and wastes, Ms Agnes Callamard, Special Rapporteur on extrajudicial, summary or arbitrary executions; Mr Michel Forst, Special Rapporteur on the situation of human rights defenders; Mr David Kaye, Special Rapporteur on the promotion and protection of the right to freedom of opinion and expression; Mr. Clément Nyaletsossi Voulé, Special Rapporteur on the rights to freedom of peaceful assembly and of association; Mr. John H. Knox, Special Rapporteur on human rights and the environment; Mr. Léo Heller Special Rapporteur on the human rights to safe drinking water and sanitation.

The UN experts are part of what is known as the Special Procedures of the Human Rights Council. Special Procedures, the largest body of independent experts in the UN Human Rights system, is the general name of the CouncilÂs independent human rights monitoring mechanisms. Special Procedures mandate-holders are independent human rights experts appointed by the Human Rights Council to address either specific country situations or thematic issues in all parts of the world. The experts are not UN staff and are independent from any government or organization. They serve in their individual capacity and do not receive a salary for their work.