The state legislature in the central Indian state of Madhya Pradesh has approved a law aimed at making religious conversions harder there.
Human rights activists fear the law will target minorities
The law says a person wishing to convert and the priest conducting the ceremony will have to inform the authorities in advance.
Religious minorities and human right groups have opposed the law saying it seeks to appease radical Hindu groups.
In May, the Pope condemned attempts to ban religious conversions in India.
The new law provides for a year in prison and cash fines to the person who converts and the priest who conducts the ceremony without informing the authorities.
The existing law on religious conversion in Madhya Pradesh passed in 1968 does not seek any such information and does not include priests in its ambit.
The BBC's Faisal Mohammed Ali in Bhopal says conversion is a major political issue in the state with the right-wing Hindu political parties accusing Christian missionaries of converting tribal people and low caste Hindus through "force and allurement".
Christian groups say the new law is "clearly directed against the church" - the punishment for the priests who do not inform authorities about a conversion ceremony is stiffer than of the person who converts.
A spokesperson for the Catholic Council of Bishops, Father Anand Muttungal, said the new law will increase "moral policing" by right-wing Hindu groups and "lead to more communal tension".
Civil liberties groups are also up in arms against the new law.
Rights activist Lajj Shankar Hardenia said the information provided by people who wanted to convert and the priest could be "misused" by radical Hindu groups.
Our correspondent says that there have been reports of attacks on churches and Christian priests by radical Hindu groups during the past two years in Madhya Pradesh.
The Hindu nationalist Bharatiya Janata Party (BJP) has ruled the state for the past two years.
In April, the western Indian state of Rajasthan, also ruled by the BJP, approved a law aimed at checking religious conversions there.
The main opposition Congress party had alleged that the legislation would target religious minorities in the state.