The University's Registrar Abu Bakar Siddique told bdnews24.com that the decision was taken at a syndicate meeting on Wednesday night.
All of the expelled students belong to the 42nd batch of the marketing department of the university . They are Sami Rezwana, Samiya Akter Nitu and 'Rafiya'of the Sheikh Hasina Hall.
According to Siddique, the three students 'physically and mentally' tortured a student of their department's 43rd batch.
The victim informed VC Farzana Islam about the matter in writing.
Sheikh Hasina Hall Provost Farid Ahmed said the three were show-caused and the matter was then raised at a disciplinary committee meeting on Tuesday.
The committee recommended expelling them as it did not find their explanations satisfactory, he added.