Free drinking water will be available to pupils under the new law

The law lays down nutritional standards for all food and drink served in schools and allows councils to provide free milk and healthy snacks.

Attempts to introduce universal free school meals were rejected.

The Association of Head Teachers and Deputies in Scotland and anti-poverty campaigners had been demanding that all youngsters be given a free lunch.

However, a bid to achieve this by Socialist MSP Frances Curran was overwhelmingly voted down by MSPs.

The issue was debated in Holyrood weeks after First Minister Jack McConnell pledged to increase the number of children eligible for free school meals by almost 100,000 if Labour wins the May elections.

We want to target resources where they are needed the most Hugh Henry Education Minister

SNP education spokeswoman Fiona Hyslop argued the new law should allow pilot projects for free schools meals to be introduced in some areas.

However, Education Minister Hugh Henry stressed that the new legislation was about ensuring school food met nutritional standards.

"This is not a bill about free school meals," he said.

"We do not support universal free school meals for all, we do want to target resources where they are needed the most and that is what we are doing."

Councils will have a duty to ensure the anonymity of those eligible for free school meals.

The new law requires that free drinking water is made available to every pupil.

'Right direction'

Mr Henry said he hoped the changes would see children become "ambassadors" of healthy eating and influence the rest of their family.

The Scottish Executive said the issue of fast food vans trading outside schools remains a matter for local authorities.

Audrey Birt, director of Diabetes UK in Scotland, said: "This move and the recent Ofcom decision to ban junk food advertising during children's programmes are steps in the right direction but much more needs to be done, and now.

"The number of children with Type 2 diabetes is soaring and this is strongly related to poor diet and lack of physical activity.

"Families need to understand the importance of a healthy lifestyle in preventing ill health and be given the support they need to help their children make healthy choices."