A lack of funding has forced some school breakfast clubs to close down and many more could follow suit, a survey suggests.
One in eight school staff (12%) say their school operated a breakfast club for pupils in the past, according to a survey by Kellogg's.
Half of these (51%) cited budgetary constraints as the reason for the closure, with just over two in five (43%) saying it was down to poor student attendance.
The poll, which questioned more than 700 school staff, reveals that many fear their breakfast club could face closure in the future, despite boosting pupils' concentration and improving their behaviour.
Some 98% said eating a good breakfast leads to better concentration, while 83% said it leads to better behaviour and 77% said it leads to higher academic achievement.
One in six (15%) primary school pupils attend a breakfast club, the survey suggests, along with 13% of secondary school students.
Overall, seven in 10 (71%) of the school staff questioned said that their school runs a breakfast club. But of these, almost half (45%) said that budget concerns could put it at risk of closure.
Nearly four fifths (79%) of the staff surveyed who said they do run breakfast clubs said they thought that closing it would lead to decreased concentration among pupils. Almost two thirds (62%) thought that pupils would achieve less and more than half (52%) said behaviour would worsen.
The survey suggests that on average, nearly a third (32%) of secondary age pupils and 17% of those at primary school are not thought to eat a good breakfast.
Bruce Learner, head of corporate responsibility at Kellogg's, said: "We decided to launch this campaign to help existing breakfast clubs as we've had a constant stream of schools contact us to say their breakfast clubs are closing and we know what a vital service they provide to children, parents and teachers."