More than half a million extra school places will be needed in the UK over the next five years as a result of immigration, a pressure group has said.
Ministers say the demand for school places is an "immediate priority"
MigrationWatch says the number of children born in the UK to parents from abroad has more than doubled in 10 years and is expected to keep rising.
But the Institute for Public Policy Research disputed the research, saying it made "questionable assumptions".
The government says it is committed to reducing the level of net migration.
The group, which advocates immigration controls, says the number of school-age migrants entering the UK is also up.
After studying immigration and population growth using government data and forecasts, MigrationWatch estimates 550,000 extra school places will be needed by 2015 at a cost of £40bn.
That figure would rise to £100bn by 2020, and £195bn by 2035, raising questions as to whether enough places can be provided, it adds.
MigrationWatch chairman, Sir Andrew Green, says the figures are a consequence of some of the most "reckless and unpopular" government policies in generations.
"The public are waking up to the speed and scale at which fundamental changes are being forced upon them, thanks to the policies of the previous administration, and our schools are but just one example," he says.
"It will be replicated in many areas of our national life such as health, housing, natural resources and infrastructure and the costs will continue to increase for many years to come."
Tim Finch, head of migration at the Institute for Public Policy Research, said the research was based on "guesstimates" which made a number of assumptions, including that migrant children would spend the maximum amount of time in the education system.
Half of the children referred to in the figures are also those whose mother was born abroad, but whose father was UK-born.
Mr Finch added: "Most of the migrants in the UK are working and paying tax and the deal in society is as long as you are doing that, we will educate your children.
"The thrust of this report is "these people are coming here and taking our school places," but they are contributing to a growing economy, so we should educate their children."
Ministers say they are "transforming" the school building programme to best meet demand, which they describe as an "immediate priority".
A government spokesperson says: "We are fully committed to reducing the level of net migration back down to the tens of thousands rather than the hundreds of thousands.
"And we will take action across the board to ensure only the brightest and the best can come to the UK."
Leave your comments please. Thanks.