The Scottish Government yesterday said it had no plans to plug a long-standing legal loophole that could hinder its flagship policy to introduce lower class sizes in primary schools.

The statement came after a local authority announced that it would not be observ- ing the targets because they were not backed up by legislation.

The SNP currently wants local authorities to reduce class sizes in the first three years of primary school to just 18 to improve the quality of education.

However, as The Herald revealed last year, the only primary class size underpinned by the law is 30 - contained in regulations passed in 1999.

As a result, any parent can get their child into any primary school under a placing request, as long as the maximum class size does not exceed 30.

Although the legal position impacts on all primary schools, it is particularly important for those in popular areas, such as East Renfrewshire.

Yesterday, officials from East Renfrewshire said class-size limits of 25 would no longer apply because of the legal position and that they were reverting to the statutory maximum of 30.

Keith Brown, the schools minister, said there was still no plan to change the law, but ministers would continue to observe the situation.

"Placing requests are a legal right that parents have, and it is obviously something that the government will keep a weather eye on," he said.

"However, there are no current plans to close this particular opportunity for parents to have their children placed in other schools."

The minister insisted no council was exempt from the class-size commitment, and said all councils had signed up to the "concordat" with the Scottish Government which agreed that progress would be made "year on year" to reduce class sizes.

A spokesman for East Renfrewshire said: "This year, we have decided to work to the statutory maxima of 30 in the first three years of primary school, where we had previously worked to a figure of 25. If we kept to the figure of 25, we would be open to legal challenge as previous judgements have proved."

Rhona Brankin, education spokeswoman for the Scottish Labour Party, blamed the class-size increases on the amount of money available to schools.

"Class sizes are going up for one reason only and that reason is the SNP's education budget, which is the worst since devolution," she said.

"This government has not given councils one extra penny to reduce class sizes. Instead, the SNP is nowhere near meeting its promise to reduce class sizes and we have seen teacher numbers reduced by a thousand in the past year.

"Schools do not have legal backing to turn people away and, if the SNP was serious about meeting its pledge on class sizes, it would pass legislation giving local authorities legal protection for maximum class sizes."

The legal ruling underpinning the current position was revealed last year in The Herald.

A mother won a placing request appeal to send her daughter to the primary school of her choice, despite the fact West Lothian Council had blocked the move, claiming the class group was already full.