Jadavpur: A young woman from Shillong studying in a reputable college in south Calcutta was allegedly molested by an unidentified motorbike rider while walking down a lane near Tollygunge on Thursday evening.

The woman, a student of microbiology, immediately reported the incident to police through Facebook and gave them a crucial lead: the last four digits of the motorbike's registration number. She did not see the man's face because he came from behind, allegedly groped her and sped away. The accused was in a white T-shirt, she said.

An officer at Jadavpur police station said the woman was targeted while walking down Graham Road towards NSC Bose Road around 7.40pm. She had stepped out of her rented apartment near Jubilee Park, off Tollygunge, a little earlier to take an autorickshaw ride to Azadgarh.

Based on the complaint posted on the police's Facebook page, Lalbazar referred the case to Jadavpur police station. "The woman said she tried to run after the bike but could not catch the offender. There was nobody else in the lane she mentioned," the officer said.

"We are checking if there is any CCTV footage from that area which will be of help," the officer said.