The state has some of the strictest anti-conversion laws in India.

One of those arrested was a professor at a Catholic theological college. The group said it was only visiting villages to sing songs.

A car used by the carol singers was also set on fire, allegedly by right-wing activists.

Police have also filed a case against those accused of torching the car.

• Indian Muslim fear conversions to Hinduism

• India parliament protest over conversions by Hindu groups

In the complaint, the resident said that the group, including the professor, had previously asked him to "worship Jesus Christ" and had offered him money to convert.

However, the Catholic Bishops' Conference denied the allegations of forced conversions, saying the group was there just to sing Christmas carols.

In Madhya Pradesh, which is governed by the Hindu nationalist Bharatiya Janata Party, people need to give formal notice in advance to the authorities to change religion.

Some Christians say this leaves villagers open to harassment by Hindu right-wing groups.

In recent years, the state has seen a surge in allegations about the harassment and intimidation of religious minorities.