A priest has been sentenced to 40 years in jail for repeatedly raping a 12-year-old girl at his church in India’s southern state of Kerala.

According to special prosecutor Pious Mathew, Sanil K. James was convicted of sexually assaulting and raping the girl at a Salvation Army church in Kerala in 2014. The priest had raped the girl several times inside the church complex over a period of two months.

"The court said the priest deserved the maximum punishment for this cruel act," Mathew said on Wednesday.

The judge ordered that James should not get remission and also imposed a 20,000 rupee (USD 295) fine, the prosecutor noted.

Judicial sources say the 37-year-old priest was given two 20-year sentences, one under India's stringent Protection of Children from Sexual Offences Act and one under a separate section of the criminal code covering the rape of children.

James was also being probed for the alleged rape of another girl during the same period.

Reacting to the ruling, Smriti Minocha, director of women's justice initiative at the Human Rights Law Network, a Delhi-based NGO said that the length of the term was highly unusual in a country where even those sentenced to life usually only serve 14 years.

"Courts normally award life sentences to rape convicts but sentencing him to 40 years is exceptional," AFP quoted Minocha as saying, who added, "Most of the cases of child sexual abuse remain undocumented. It's only grave acts like rape and molestation which are reported."

Child sexual abuse is common at homes, schools and residential care facilities across India.

Indian students hold placards during a rally to mark the second anniversary of the fatal New Delhi gang-rape of a student inside a moving bus, in Mumbai, India, December 16, 2014. (Photo by AFP)

According to India's national crime records bureau, more than 18,000 children were sexually assaulted in 2014.

A UN Committee on the Rights of the Child in 2014 said it was alarmed by widespread violence and sexual abuse of children in the South Asian country. It added that one-in-three rape victims in India was a minor and half of the abusers were in a position of trust and responsibility.

Critics maintain New Delhi authorities have a poor record in bringing offenders to justice.

India has toughened punishment for sexual violence since the fatal gang-rape of a student on a Delhi bus in 2012. The death sparked mass protests in the country as well as domestic and international outrage.