The Indian prime minister, Narendra Modi, has broken his months-long silence on the deadly ethnic conflict raging in the state of Manipur after a video emerged of women being stripped naked, paraded and assaulted before it is alleged they were gang raped. Outrage erupted across India after footage was circulated from Manipur of two women from the minority Kuki tribe being forcibly stripped naked by a mob of the majority Meitei tribal group who can be heard shouting: “If you don’t take off your clothes, we’ll kill you.” The women are then publicly groped and dragged to a field, where it is alleged they were gang raped. The incident took place in early May and although it was registered with the police soon afterwards, it was not until Thursday that four arrests were made, a day after the video went viral. One of the victims has alleged the police left the women in the hands of the mob. Speaking at the opening session of parliament on Thursday morning, Modi made his first comments about the conflict being fought between the Meitei and the Kuki tribes, and stated that “the entire country has been shamed” by the attack on the women. “I want to assure the nation, no guilty [people] will be spared,” he said. “Action will be taken according to the law. What happened to the daughters of Manipur can never be forgiven. As I stand next to this temple of democracy, my heart is filled with pain and anger.” Modi has been criticised for remaining publicly silent on the conflict, which broke out between the tribal communities in early May and has since killed more than 140 people, mostly those from the minority Kuki community. The state of Manipur is now essentially partitioned down ethnic lines, with the Meitei community in the valley and the Kuki community controlling the hills. Both sides have assembled civilian forces that continue to clash violently with thousands of stolen weapons, while villages have been burned to the ground and more than 60,000 people displaced. Thousands of Indian armed forces have been deployed to the state to maintain calm but the Kuki minority now say they are fighting for an independent state. One of the victims in the video told the Guardian she had been traumatised by the events that took place. She described how she and four others had been running away from their village, which had been looted and set alight by a Meitei mob, when they were set upon by another Meitei gang, who then murdered two members of their group. “Me and another girl were taken away,” she said. “They encircled us and told us to remove all our clothes. I tried to plead with them to leave us alone but they warned us that we would get killed like our neighbours if we don’t obey them. I did what they told me to do, they were ready to kill us otherwise. They then paraded us. Men were touching my breasts and all over my body.” She added: “We were taken to a nearby field. I do not want to get into the details but after that I was let go.” The video also attracted fierce criticism from the supreme court, which called it “deeply disturbing” and a “gross constitutional failure”. The chief justice of India, Dhananjaya Chandrachud, appeared to criticise the government for failing to bring the situation in Manipur under control. “I think it’s time that the government really steps in and takes action because this is simply unacceptable,” he said, adding that if the government did not act, the supreme court would step in. Other ministers from Modi’s government also condemned the incident. Smriti Irani, the minister for women, called it “downright inhuman” and said the perpetrators would be brought to justice. But activists were critical that it had taken such an extreme video for outcry at the situation in Manipur to be voiced by the prime minister and the public. “It is shameful that it takes a searing video of two Kuki women being paraded naked and raped to shake the conscience of the world and make people believe what we have been saying for the past 70 days,” said Golan Nulak, a Kuki activist.