Companies cannot advertise available roles by stating a preference for a particular age group.
This is according to HR firm Think Resources, which pointed out that to do so constitutes discrimination, the Cambridge Network reports.
However, it added: "A candidate cannot claim age discrimination based on just seeing the advertisement - they ... have to have been rejected on the basis that their age did not fit with the specified criteria."
Jobseekers may also be able to make claims of discrimination if they are asked certain things during the interview process on the basis of which they are ruled out for the role.
For example, if a firm asks things like how an applicant would feel taking orders from a younger colleague or why they are applying for the position at their time of life, they may be breaching employment laws.
Questions referring to a person's youth may also fall into this category, Think Resources said.