West Bengal Education Minister Partha Chatterjee also went on to add that lesbianism is "against the ethos" of the state.
"In the past, we had never received reports of such incidents in the state's educational institutions. If such an incident (lesbianism) had indeed happened, it would be against the ethos of our state.
"I will ascertain from the school management what prompted them to secure the written admission from the students," said Mr Chatterjee while responding on the incident in south Kolkata's Kamala Girls' High School.
The school's acting headmistress had on Monday claimed that the students admitted that they had indulged in lesbian act within the school premises. The school then asked them to admit it in writing, which these students did.
The parents, however, rubbished the allegations. "If two persons hold hands, or put an arm on each other shoulders, that does not mean they are lesbians," a guardian told IANS.
Mr Chatterjee said the government was not treating the issue lightly, as it was unprecedented in the educational institutions of the state.
(with inputs from agencies)