A panel of experts commissioned by the Scottish Executive to look into the dietary value of school meals in Scottish schools is expected to call for substantial restrictions on the promotion and sale of carbonated soft drinks in secondary schools.

The panel, which is to report officially next month, is thought to have concluded that carbonated soft drinks damage the academic performance of pupils.

"There has to be a real determination to wean pupils off the habit of drinking Coke, Irn Bru and the like," said Michael O'Neill, director of education at North Lanarkshire council and chairman of the expert panel, adding that the evidence was now undeniable. A number of education authorities have already stopped serving carbonated drinks to pupils at school lunches in accordance with guidelines drawn up by the panel last year.

Thinking on this subject has been influenced by research in the US which has suggested that teenagers who consume large amounts of caffeinated, fizzy drinks were more likely to suffer sleep deprivation and lower levels of concentration, while those pupils who drank fewer carbonated drinks showed better results.

However, schools have been reluctant to remove drinks machines because of the profit-sharing deals on offer which can, in some cases, allow a large secondary school to make up to £12,000 a year from just one machine.