"We strongly condemn the incident that took place at the Ranaghat Convent," she said.
"We have ordered a CID probe. The agency will be examining all aspects of this horrific crime. Swift, strongest action to be taken against the culprits", the Chief Minister added.
Reports said the a gang of dacoits broke into the convent at Gangapur under Ranaghat sub-division in Nadia district around 12:30 am and raped the 71-year old nun after gagging her.
They later decamped with cash worth Rs 12 lakh.