A committee of MPs has warned that the quality of children's education may be affected by the rush to increase primary school places by September 2013.
The Commons Public Accounts Committee said central and local government have failed to act fast enough to cope with the dramatic rise in demand for primary school places in England, where some 250,000 places are needed for next term.
The committee says the situation could lead to under performing schools expanding in the struggle to find spaces for children.
"The department does not sufficiently understand the risks to children's learning and development that may arise as authorities strain the sinews of the school estate to deliver enough places," the reports states.
"The imperative to increase the quantity of school places should not be achieved at the expense of quality."
Margaret Hodge, the committee's chair, said the effect on children's learning needed to be considered when specialist facilities and areas were being turned into regular classrooms.
"It does not take much imagination to realise that educational opportunities and standards might be diminished if specialist areas, such as music rooms and libraries, are converted into classrooms, poorly performing schools expanded, or playgrounds used to house children in overcrowded [temporary structures]."
The Department of Education said that the Government has already doubled spending on new school places, and that the issues stem from the previous administration.
"Margaret Hodge is right that there is a severe need to ensure there are enough school places but she has failed to pin the blame where it belongs - at the door of the last government of which she was a member," said Schools Minister David Laws.
The Government said on Thursday that it would be spending £7.5bn to create500,000 additional school places by 2021.