The firing in Thoothukudi was the deadliest at an environmental protest in India in a decade (FILE PHOTO)

Tamil Nadu police used just 43 non-lethal bullets - 18 rubber and 25 plastic - before firing 69 rounds of live ammunition, a National Human Rights Commission inquiry into the deadly crackdown on demonstrators protesting against Vedanta's copper smelter in Tamil Nadu in May last year has found. At least 13 people were killed in the operation in Thoothukudi. The non-lethal bullets were "too less to have been effective", the report accessed by NDTV through a Right to Information or RTI request, said.

Twelve of the 13 protesters killed when police opened fire on May 22, 2018 were hit by bullets in the head or chest, and half of those were shot from behind, autopsy reports had said earlier.

Based on media reports, the National Human Rights Commission or NHRC had ordered a probe into the alleged use of excessive force by Tamil Nadu Police. Based on Delhi High Court's direction, the NHRC also sent their investigation team to Thoothukudi to probe the allegations. The NHRC team conducted submitted its report to the commission last year.

The NHRC probe team found that "non-lethal bullets used were too less to have been effective" and also called for a "detailed investigation on quantum of force used to control the crowd at individual places."

Despite this, the NHRC decided to close the case saying the Tamil Nadu government-constituted "Judicial Commission is already looking into the allegation of excessive use of police force, hence no further intervention needed."

"The location of injury on the head and vital organs on upper part of the body of the deceased / injured does appear to give some credence to the allegation of excessive and indiscriminate use of firepower," the NHRC report said.

But the report also said, "The situation could have become worse and led to loss of human lives if force had not been used."

Though 1,182 police personnel, including the Inspector General of Police Southern Sector, were put in place to deal with the situation, the NHRC team found that the "administration underestimated the turn out of the people and the extent they might go".

In total, 26 tear gas shells, 18 rubber bullets and 25 plastic bullets were used before 69 rounds of live ammunition, by the police over one hour and fifteen minutes, the report added.

Thirteen people were killed and more than 100 were injured including 30 with gunshot injuries, it said.

Police rules in India allow the use of live ammunition to counter civil unrest, but say that the response should be proportionate and officers should not shoot to kill. Police Standing Orders for Tamil Nadu say that, when using firearms, "aim should be kept low, preferably well below the waist level, and directed against the most threatening part of the mob".

The firing in Thoothukudi was the deadliest at an environmental protest in India in a decade. A working group of United Nations' human rights experts in May condemned the "apparent excessive and disproportionate use of lethal force by police".

The Central Bureau of Investigation or CBI is investigating the shootings, which took place as protesters were marching to the local government headquarters in the port city, demanding that the Sterlite copper smelter controlled by London-headquartered Vedanta Resources be shut for allegedly polluting the environment.

No police officers have been arrested or charged in connection with the killings. In a statement following the incident the Tamil Nadu state government, which is responsible for the police, said: "Due to unavoidable circumstances, we had to take action to bring the situation under control."