Universities could face a "flood" of claims under legislation that outlaws discrimination on the grounds of sexual orientation or religious belief because they are not prepared.
Kate Heasman, equality official for lecturers' union Natfhe, said institutions had failed to realise that large sections of the Employment Equality (Sexual Orientation) Regulations 2003 and the Employment Equality (Religion or Belief) Regulations 2003 acts applied to them. Both will come into effect next week.
Although the laws apply to staff and students in the higher and further education sectors, the government had offered no consultation or advice, Ms Heasman said, only "complete silence".
This week, the Equality Challenge Unit published a guide to the legislation, days before the acts come into effect.
Erica Halvorsen, the unit's policy adviser, said most universities were already dealing satisfactorily with these issues. They are required by the Race Relations Amendment Act to promote good race relations and equal opportunities.
But Ms Heasman said most universities had not considered that students could now object to having to sit an exam or attend a lecture scheduled for Saturdays, for example, because it is the Jewish Sabbath.
Evangelical groups that handed out homophobic literature on campus would also be breaking the law.
While cases of a religious nature may be more common, Ms Heasman added that there were many gay and lesbian activists who might seize the opportunity to use the new laws to draw attention to their cause.
"It could open the floodgates. There will be people who want to prove a point," she said.
The union called on the government to make representations to the sector and to hold training courses as soon as possible.
The Equality Challenge Unit guidelines say universities and colleges should take action that includes assessing the demand for food that meets religious dietary demands, such as kosher or halal dishes, and provide it "according to the demand".
It adds that the sexual-orientation legislation protects everyone, including those believed to be of a particular sexual orientation, whether or not they are.
Staff must still work in accordance with their contract and are not entitled to time off for religious observance. Neither do institutions have to monitor for staff sexual orientation.