Inspectors are investigating claims that many primary-aged children are no longer being taught history and geography because schools are concentrating on the basics to meet ministers' targets.
The primary division of the Office for Standards in Education has surveyed 50 schools to assess whether these subjects are disappearing from the primary timetable.
The findings will not be known for some weeks, but alarm bells are said to be ringing in the Department for Education and Employment, where similar concerns are being voiced privately by David Blunkett's advisers.
Last year OFSTED found evidence that too many lessons in maths were much longer than recommended and this was having an adverse effect on other subjects.
Those complaining publicly about the distortion of timetables include David Hart, general secretary of the National Association of Head Teachers. The issue is expected to be raised this weekend at the association's primary conference in York.
Mr Hart said: "The Government is talking about curriculum enrichment, but the reality is that the focus on numeracy and literacy means schools cannot provide a broad and balanced education."
Since the introduction of the literacy hour and the daily maths lesson test scores for 11-year-olds have risen dramatically. According to the latest figures, three-quarters of children now reach the required standard in English and 72 per cent in maths.
Schools are on course to reach the literacy and numeracy targets for 2002, but ministers have already set even higher ones for 2004, while insisting that they also provide decent lesson time for geography, history, the creative arts, sport and music.
"I'm appalled at the suggestion that there are to be new targets, when th Government is not apparently willing to look again at performance tables. If the goalposts are being moved, we need accurate tables. As they stand, absent pupils are recorded as having a zero score and that clearly is not fair," said Mr Hart.
Peter Frost, chief executive of the National Primary Trust educational charity, which holds its congress in Birmingham next week, said that there was a danger that the literacy and numeracy strategies would deskill teachers.
"At one level, we have teachers better-equipped to teach the basics - they are very good technicians - but they don't have the skills to develop creativity in their pupils," he said.
Cynics suggest that ministers are turning a blind eye on schools that spend more than the two hours a day on the basics because of the priority attached to literacy and numeracy. They point out that the advice prepared last year by the Qualifications and Curriculum Authority to help schools find room in the time-table for all the subjects in the national curriculum has been blocked by ministers. The advice will go to schools later this year, but so far no date has been given.
Education consultants say teachers are focusing on pushing up test scores. Roger Cole, who visits around 100 schools a year, says children are being asked to perform beyond their capabilities.
He said: "In the confident schools, they are teaching literacy and numeracy more effectively and making sure children have a broad and balanced education. But at a significant number of others, they are bettering results and the rest of the curriculum is on hold."
The DFEE rejected the idea that the strategies have squeezed out other subjects. A spokesman said: "Unless children can read, write and do basic maths, they are not capable of dealing with other subjects. The balance was skewed against the basics in 1997 and we have given them their proper place in primary schools."