Sikh activists have filed a lawsuit in New York demanding the United States blacklist as a terrorist organisation a hardline Hindu group linked to India's ruling party. The federal court issued a summons for US Secretary of State John Kerry to respond to the suit within 60 days, according to court papers sent to media on Wednesday by US-based advocacy group Sikhs For Justice. The 26-page complaint likened Rashtriya Swayamsevak Sangh (RSS) to Nigeria's armed militants Boko Haram. It held the RSS, the ideological mentor of Prime Minister Narendra Modi's Hindu nationalist Bharatiya Janata Party (BJP), responsible for instigating multiple acts of violence. The Sikh activists accused RSS of "running a passionate, vicious and violent campaign to turn India into a Hindu nation with a homogeneous religious and cultural identity". A New York judge last week dismissed on grounds of immunity a lawsuit that accused Modi of "attempted genocide" over deadly 2002 anti-Muslim riots that killed at least 1,000 people. Gurpatwant Pannun, legal adviser to Sikhs for Justice, said they filed the suit after Kerry failed to respond to a written request last month for the State Department to blacklist RSS. The group came under fire last month after 200 Christians were converted en masse in Modi's home state, fanning concern at the right-wing government's perceived pro-Hindu tilt. Kerry held talks with Modi in India this month, hailing him as a "visionary".