More than one in five of England's primary schools are full to bursting point, government statistics reveal.
Some 20.3% of state primaries, 3,444 in total, are full or have more pupils than they should, Department for Education figures show.
The numbers are up on last year, when just under a fifth (19.8%), some 3,376 primaries were full.
It follows claims any schools funding increases from the spending review will be wiped out by rising pupil numbers.
Analysis by the Institute of Fiscal Studies suggests per pupil funding will fall in real terms by 0.6% per year because of expected increases in pupil numbers.
The new figures will also revive concerns about a lack of school places in some parts of England, particularly in big cities such as London and Birmingham.
'Booming birth rates'
The statistics also show that 29.3% of state secondaries, 916 schools in total, are full or have pupils in excess of school capacity, compared to 28.8% in 2009.
The figures come as parents across England submit applications for secondary school places.
The deadline set by many councils for applications is the end of this week.
The Local Government Association has been estimated that around £15bn is needed over the next four years to guarantee every child a school place in a safe environment
LGA chairman Baroness Margaret Eaton said: "Everyone is well aware of the difficult financial climate in which councils are operating.
"We need to work even harder to ensure that the money that is invested in school buildings represents the best possible value for the taxpayer.
"Our children need schools which are safe, clean and attractive places in which they can learn.
"Spending money to maintain or replace existing school buildings is unavoidable.
"Areas experiencing booming birth rates need to be able to expand primary schools so that every child has a place not too far from their home."
A survey earlier this month suggested that thousands of children were still waiting to be allocated a school place a month after the new autumn term started, as councils in many areas faced problems accommodating them.