New Delhi (CNN) A group of nuns in one of India's oldest Catholic communities is calling for the arrest of a bishop who has been accused of raping one of the church's sisters multiple times over a two-year period.

The case in the southern state of Kerala has attracted international attention, as it is extremely rare for nuns to publicly accuse a superior of wrongdoing, let alone sexual assault.

Five nuns have been protesting outside the Kerala High Court, which is hearing the case, calling for Bishop Franco Mulakkal to be arrested and the investigation to be expedited.

More than 100 citizens have come to support them since the demonstration started on Saturday, according to George Joseph, the president of the Joint Christian Council, an advocacy organization working with the nuns.

Unlike the rest of India, where Christianity remains a minority religion practiced by just 2.3% of the total population, Kerala is home to a sizable Christian community that dates back hundreds of years.

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