A 17-year-old girl has been allegedly sexually assaulted as she walked home near to Franklin College.
The incident was reported shortly before 1.30pm on Wednesday, March 7.
The victim reported she was grabbed from behind by an unknown man, who is said to have touched her inappropriately.
She is not believed to have been injured.
Humberside Police said officers are conducting enquiries to establish the circumstances of the incident, which was reported approximately 20 minutes later, and reassuring residents in the area.
Anyone with any information about the alleged sexual assault should call police on 101 quoting log number 255 of March 7.
The Grimsby Institute nearby also posted on social media about a reported abduction in the local vicinity and alerted students to be vigilant on their way home.
It is not clear if this is connected to the alleged assault. Humberside Police added there has been no report of an abduction made to them.