Image copyright Getty Images Image caption A mural raises awareness about menstruation, which has long been a taboo in India

India's uncomfortable relationship with periods is back in the headlines.

College students living in a hostel in the western Indian state of Gujarat have complained that they were made to strip and show their underwear to female teachers to prove that they were not menstruating.

The 68 young women were pulled out of classrooms and taken to the toilet, where they were asked to individually remove their knickers for inspection.

The incident took place in the city of Bhuj on Tuesday. The young women are undergraduate students at Shree Sahajanand Girls Institute (SSGI), which is run by Swaminarayan sect, a wealthy and conservative Hindu religious group.

They said a hostel official had complained to the college principal on Monday that some of the students were breaking rules menstruating women are supposed to follow.

According to these rules, women are barred from entering the temple and the kitchen and are not allowed to touch other students during their periods.

At meal times, they have to sit away from others, they have to clean their own dishes, and in the classroom, they are expected to sit on the last bench.

Image copyright BBC Gujarati Image caption Female students gather outside the Shree Sahajanand Girls Institute (SSGI)

One of the students told BBC Gujarati's Prashant Gupta that the hostel maintains a register where they are expected to enter their names when they get their periods, which helps the authorities to identify them.

But for the past two months, not one student had entered her name in the register - perhaps not surprising considering the restrictions they have to put up with if they do.

So on Monday, the hostel official complained to the principal that menstruating students were entering the kitchen, going near the temple, and mingling with other hostellers.

The students allege that, the next day, they were abused by the hostel official and the principal before they were forced to strip.

They described what happened to them as a "very painful experience" that had left them "traumatised" and amounted to "mental torture".

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One student's father said that when he arrived at the college, his daughter and several other students came to him and started crying. "They are in shock," he said.

On Thursday, a group of students held a protest on the campus, demanding action against the college officials who had "humiliated" them.

The college trustee Pravin Pindoria said the incident was "unfortunate", adding that an investigation had been ordered and action would be taken against anyone found guilty of wrongdoing.

But Darshana Dholakia, the vice-chancellor of the university which the college is affiliated with, put the blame on the students. She said that they had broken rules and added that some of them had apologised.

However, some of the students told BBC Gujarati that they are now under pressure from the school authorities to play down the incident and not to speak of their ordeal.

On Friday, the Gujarat State Women's Commission ordered an investigation into this "shameful exercise" and asked the students to "come forward and speak without fear about their grievances". The police have lodged a complaint.

Video caption Using comics to combat India's menstruation taboos

This is not the first time that female students have been humiliated on account of periods.

In a very similar case, 70 students were stripped naked three years ago at a residential school in northern India by the female warden after she found blood on a bathroom door.

Discrimination against women on account of menstruation is widespread in India, where periods have long been a taboo and menstruating women are considered impure. They are often excluded from social and religious events, denied entry into temples and shrines and kept out of kitchens.

Increasingly, urban educated women have been challenging these regressive ideas. In the past few years, attempts have been made to see periods for just what they are - a natural biological function.

But success has been patchy.

In 2018, the top court in a landmark order threw open the doors of the Sabarimala shrine to women of all ages, saying that keeping women out of the temple in the southern state of Kerala was discriminatory.

But a year later, the judges agreed to review the order after massive protests in the state.

Surprisingly, the protesters included a large number of women - an indication of how deeply rooted the stigma over menstruation is.

Read more from Geeta Pandey