Sikh activists said they filed a lawsuit Wednesday in New York demanding the United States blacklist as a terrorist organization 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 AFP by US-based advocacy group "Sikhs For Justice."
The 26-page complaint likened Rashtriya Swayamsevak Sangh (RSS) to Nigeria's armed group 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.
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."
The lawsuit comes with US President Barack Obama to be guest of honor at India's Republic Day celebrations on January 26.
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 advisor to Sikhs for Justice, told AFP 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" poised to transform the Indian economy.
India is a secular country under the constitution and religious freedom is considered a fundamental right.
But critics say Hindu hardline groups have become emboldened since the BJP was elected, promoting a Hindu-dominant agenda.
Sikhs for Justice is a small non-profit group that Pannun said was backed by "most" of the estimated 500,000 Sikhs who live in the United States.