A LEGAL change to class sizes is to be opposed this week by the Conservatives, who say the higher limit of 30 pupils should stay.
The controversial stance comes after widespread criticism of the Scottish Government for failing to meet its election manifesto pledge to reduce class sizes.
Conservative schools spokeswoman Liz Smith will tomorrow oppose new legislation that would legally lower class sizes to 25. She will argue at the Scottish Parliament's education committee that the move would reduce parental choice and have a negative effect on many youngsters.
She said: "Reducing the cap to 25 for only primary one classes presents several difficulties.
"Firstly, it compromises parental choice when it comes to placing requests and it will hinder the ability of some parents to find primary one places in good schools."
She also fears that the move would force classes above primary three to rise.
She added: "It is my belief that the current legislation is perfectly adequate and should be left alone - not tampered with by the Scottish Government whose class size policy has been full of inconsistencies and unworkable promises since day one."
Eileen Prior, executive director of the Scottish Parent Teacher Council said: "The whole issue of class sizes is smoke and mirrors.
"It's something a lot of people get very excited about, however, it's not something many parents come to us about.
"There is a sense that having clarity about the maximum class sizes would be a good thing because it will allow local authorities to say that class is full and manage resources better.
"But this reduction would effectively limit parental choice so some parents will be less than satisfied with it. What we do know is that parents are far more concerned about knowing there is good teaching in their school."
In its 2007 election manifesto, the SNP promised to reduce classes in the first three years of primary to 18 by maintaining teacher numbers.
However, removing ring-fencing of education funding to councils saw cash-strapped local authorities reduce teacher numbers and the policy has not been achieved.
The Scottish Government brought in a new target for 20 per cent of all children to be in classes of 18 or less in primaries one to three.
However, those councils which did impose lower class sizes found themselves subject to legal challenges by parents whose children had been denied a place at their chosen school because classes were full. The parents successfully argued that the only statutory limit was 30, forcing councils to accept their children and abandon lower limits.
In reaction Fiona Hyslop, the then education secretary, promised last September to make it law that a primary-one class could not contain more than 25 pupils.A Scottish Government spokeswoman said: "Small class sizes give pupils more one-on-one time with their teacher.
"Our proposals will legally limit primary one classes to 25 and it will be a mystery to parents and teachers why anyone would oppose this simple, common sense measure to improve our children's education."