Lectures and tutorials should be halted at the University of Liverpool after dozens of students tested positive for Covid-19, a union has said.
The university said 80 students and seven staff had tested positive for coronavirus in the last seven days.
The University and College Union (UCU) said it meant lessons were "likely to lead" to a further spread of the virus.
Pro vice chancellor Prof Louise Kenny said the university was safe and face-to-face teaching was "essential".
She said the institution's investment in "an on-campus testing facility for staff and students" meant it could "act quickly to stop the spread".
UCU official Martyn Moss said without urgent action, it would be "impossible for universities to avoid becoming incubators of Covid and university communities becoming transmission hotspots".
"We have been warning for weeks of the dangers of universities persisting with in-person teaching," he added.
The UCU has also called for lectures and tutorials to be stopped at the city's other two higher education sites, Liverpool John Moores University and Liverpool Hope University.