India's Catholic bishops have urged the government to stop attempts to convert Christians and others to Hinduism.

A special consultation presided over by Cardinal Baselios Cleemis was called in New Delhi aimed at responding to a series of incidents in which mass conversion or 'ghar wapsi' programmes had been carried out or threatened by nationalist Hindu parties.

A statement from the bishops addressed to the prime minister, Narendra Modi, said: "India is a land where different religious faiths have long since flourished and our founding fathers made special efforts to ensure that the rights of all are safeguarded, irrespective of our religious beliefs, gender or caste."

It said that the conversions or 'reconversions', as the instigators call them, had "hurt the sentiments of the Christian community" and "shaken the faith in the secular fabric of our nation". It warned that "Communal polarisation and the bid to homogenise India are posing a threat to all minorities – women, dalits, and all linguistic, cultural and religious minorities."

The statement said that "Conversions of a religious nature are an exercise of one's free will and one's constitutional/fundamental rights and freedom of conscience and of religion. Ghar Wapsi is a political process, carried out by the powerful exponents of religious nationalism – much against the principle of secularism."

The bishops asked for "assurance from the Government that we are protected and secure and safe in our motherland". They called on Modi to "urgently intervene and take appropriate action to stop incidents that pose a big threat to the unity of this secular nation".

A planned mass Christmas Day conversion ceremony in India's Uttar Pradesh state was banned by the state's police force.

Organised by an offshoot of the nationalist Rashtriya Swayamsevak Sangh (RSS) group, the ghar wapsi ceremony for the Muslim-majority city of Aligarh was set to convert at least 1,000 Muslim and 4,000 Christian families from the Valmiki Dalit group, which the group claims to have identified already.

However, according to the Times of India, police spokesman Amit Agarwal said there were public order considerations and announced that the ceremony would not be given permission. "Under no circumstances will we allow the proposed mass conversation programme slated for December 25," he said, adding: "The so-called 'ghar waapsi' programme organised by the Dharam Jagran Samiti can become a law and order issue for the state and irrespective of the finer details of this event it cannot be allowed to be held."