Proposals to scrap limits on class sizes in primary schools have been condemned by Lambeth council’s leader.

Councillor Steve Reed spoke out after the chief executive of Sutton Council, Niall Bolger, wrote to every council chief executive in London, urging them to consider lifting the current cap to cope with rising demand.

Primary schools are restricted to having 30 children in a class, but in boroughs such as Lambeth, schools often struggle to keep to the limit. Coun Reed, who is also the head of education at London Councils, said the proposals would lead to “less attention for every child”.

He said: “It’s wholly unacceptable that councils are being forced to consider expanding class sizes above thirty children. No parent wants this because it means less attention for every child.

“We’re in the middle of the biggest boom in birth rates for decades and the recession means fewer families are moving out of London than in the past.

“This all adds up to an explosion in the number of children needing a place in a good local school, but the Government is refusing to pay for it. It’s wrong and they need to change their minds or children across London will suffer.”

Sara Thomlinson, secretary for Lambeth NUT (National Union of Teachers), said the government needed to invest more money in the borough’s education provisions.

She said: “Class sizes are a huge issue for us and we are fighting to make them smaller, not bigger.

“When you look at private schools and the elite forms of education, they do not allow more than 20 children [in a class].

“What is good enough for private school children is good enough for our children too.”

Lambeth’s primary schools are heavily oversubscribed and the council has admitted it will not be able to guarantee a school place for every child by 2015.

St Julian’s School in Streatham is set to expand to relieve the shortage of places. A new site in West Norwood will accommodate 420 children from September 2012.