UCD has written to all of its 27,000 students to inform them of its ongoing investigation into inappropriate social media postings, warning that any breaches of the student code could result in expulsion.

In the email sent last night, the college's deputy president, Mark Rodgers, said its inquiry would determine if there was any illegal activity and this would be referred on to the relevant authorities.

Last week, university newspaper the College Tribune alleged that up to 200 male students were members of a private Facebook group used to share stories and rate photos of women.

The group was alleged to centre on Agricultural Science students.

It is understood gardaí are aware of the college's investigation.

Mr Rodgers said college authorities were working to identify the existence of the site and to identify if any students were involved in posting inappropriate images of others without their consent.

He said the Dean of Agriculture had already sought information from student representatives and contacted all students in the School of Agriculture and Food Science last week asking them to come forward in confidence.

The email said the college's primary concern was to support any vulnerable student that may feel victimised. 

However, any breaches of the student code may result in sanctions up to and including expulsion from the University.

It added that "the University expects each and every one of our students to respect the dignity of others at all times and to uphold the highest standards both individually and among their peers".  

"This particular allegation brings into stark focus the prevalence in society of postings and comments online which can cause offence and victimisation including: bullying, sexual harassment and discrimination".