A nun was sexually assaulted at the missionary-run medical centre where she worked in central India, police reported on Sunday.

The 45-year-old nun was found unconscious, with her hands tied, at the Krist Sahaya Kendra (Christ Help Centre) in the Raipur district of Chhattisgarh state in the early hours of Saturday morning.

It is not yet clear whether the assault was rape or attempted rape.

"The nun is in acute trauma and undergoing treatment," inspector general GP Singh told the Times of India. "She said two masked men entered her room in search of cash and valuables and assaulted her after they failed to find their booty."

The nun, who is a qualified nurse and a member of the Salesian Missionaries of Mary Immaculate, was living at the centre, where they treat children and patients with minor injuries.

The Times of India reports that Christians protested in Raipur city on Sunday in response to the attack.

The Catholic Bishops' Conference of India said in a statement: "Such incidents of violence on minorities and especially women, tarnishes the image of our country in the international community, besides posing serious questions as to how far the minorities are safe and secure today in India."

In March, an elderly nun was gang-raped at a convent in West Bengal, coinciding with a number of attacks on churches in Delhi, which prompted protests over the lack of protection for religious minorities in India under the current government.

The government subsequently said that the rape and the attacks on churches were not religiously motivated, seeking to dispel claims that the attacks were influenced by a Hindu nationalist political agenda.