Indian authorities are investigating a report that 50 to 100 Christians have been forcibly converted to Hinduism. One of the incidents reportedly took place on Wednesday when 50 people from both Christian and Muslim communities were “reconverted.” The ceremony was organized by the country’s nationalist group Vishnu Hindu Parishad (VHP).

“The worry is that some kind of coercion is involved. The communities [involved in the recent incidents] are already vulnerable and the campaign seems quite aggressive and the combination is concerning,” Meenakshi Ganguly, South Asia director of Human Rights Watch, told the Guardian.

Conversions are illegal in India if they are coerced or bribery is a contributing factor. “Reconversions” like the one that reportedly took place on Wednesday often make promises to participants, including monetary compensation and priority access to the country’s welfare programs.

“Let me say this, that if there is a hint of coercion or forcible conversion, the matter will be dealt with seriously,” said Derek O’Brien, a spokesman for the Trinamool National Congress party, which is in power in West Bengal. He added that officials have launched an inquiry into Wednesday’s ceremony.

VHP has claimed responsibility for Wednesday’s ceremony. “We are not committing any sin by bringing back our people to our own religion. This is a service to our country,” VHP general secretary Jugal Kishore told India Express, referring to the conversion program known as “ghar wapsi,” or “homecomings.” VHP organized at least two other “ghar wapsi” events in the past two months. One took place on Jan. 18 when 27 Christians were reportedly “reconverted” to Hinduism. In December, VHP said it performed the ceremony on 50 people in Kerala, NDTV reported.

“Ghar wapsi” is meant to bring religious minority groups “back to Hinduism, back to their original home,” Dharm Narayan Sharma, central secretary of VHP, told the Daily Beast. Roughly 80 percent of the country’s 1.24 billion people are Hindu; 13 percent are Muslim, 2.3 percent are Christian and 1.8 percent are Sikh.  

Nationalist groups like VHP claim that Indian Christians and Muslims are descendants of Hindus and at one point in time were deceived into following a different faith. The mass conversions are meant to bring them back into the fold.

Mass conversion ceremonies have been gaining prominence since the election of Prime Minister Narendra Modi, a Hindu nationalist, in May. He has not publicly commented about the mass conversions and warned members of parliament and ministers to not do so either, fearing it will distract from his development agenda, the Guardian reported.

News of the mass conversions comes on the heels of President Barack Obama’s visit to India earlier this week. During his final speech, he urged Modi to push for social changes, including women’s rights and religious tolerance.

“In our lives, Michelle and I have been strengthened by our Christian faith. Still, as you may know, my faith has at times been questioned — by people who don’t know me — or they’ve said that I adhere to a different religion, as if that were somehow a bad thing," Obama said in a speech to New Delhi youth on Tuesday. "Every person has the right to practice their faith how they choose, or to practice no faith at all, and to do so free from persecution and fear."