Tens of thousands of students are achieving decent GCSE grades in maths, but are being turned off from studying the subject to a higher level, a report suggests.
More must be done to encourage teenagers to continue studying maths after the age of 16, according to a new discussion paper by the Advisory Committee on Mathematics Education (ACME).
Many pupils do not continue to study the subject because they would rather choose another course, it says.
And others are prevented from continuing their maths studies because they did not get good enough grades at GCSE, or sat an exam that failed to cover enough material.
The paper, which was discussed at ACME's annual conference in London today, suggests that in England there has been "some success" in boosting the numbers studying maths beyond GCSE.
Last year, around 80,000 students were entered for A-level maths, and this is predicted to rise to 100,000 this summer, it says.
But it warns: "Despite these encouraging trends, England still lags behind the rest of the world in terms of post-16 participation in mathematics, and the effects of this are being felt in higher education and in the workplace.
"Each year there are 250,000-plus students who achieve a grade B or C at GCSE, but who do not, or cannot, take a mathematics course post-16. These students have achieved a good GCSE grade by league table standards, but in mathematics they are effectively disenfranchised.
"Some students choose to study another subject rather than mathematics; some simply do not wish to continue their studies. However for others, access to a well-recognised qualification is effectively denied either because they have not covered appropriate content in a foundation-tier GCSE, or because they did not gain a grade C or B at GCSE and are discouraged from taking A-level.
"A very few have access to the existing provision offered by FSMQs (free-standing mathematics qualifications) and AS-level Use of Mathematics.
"Put simply, the vast majority of young people have no widely recognised way of continuing to study mathematics after GCSE. This paper considers how this situation could be changed."
The paper sets out a number of ways to encourage youngsters to continue to study beyond GCSE.
One method would be to include maths in other qualifications, so that pupils would not have to study a separate maths course.
This would help students to understand how maths relates to other subjects, the paper suggests, but it would not work for every subject, like English.
It also says the government could consider introducing a Baccalaureate-style qualification, with pupils studying a number of subjects including compulsory maths.
Other options could be to introduce a new qualification, in between GCSE and AS-level maths, or reforming the AS-level to make it possible for students with a C at GCSE to take it.
In his speech to ACME's conference this afternoon, schools minister Nick Gibb said that maths is "an essential part of every child's educational armoury".
"As fundamental to our day-to-day lives as the ability to read, maths allows us to navigate the world by calculating uncertainties and predicting outcomes; spotting patterns and irregularities; by making sense of the calculations of others," Mr Gibb said.
"It is also to mathematics that we look first to provide opportunities in study and employment. It is the skeleton-key subject: opening doors to other disciplines and jobs from archaeology to architecture, engineering to economics, genetics to geology."
Mr Gibb told delegates that the government sees maths as more than "a subject that we take to simply to gain employment or pass an exam".
"There is - as we all know - great beauty, fascination and depth to maths. The reoccurrence of patterns in nature. The symmetry of great music and art. The inter-related numbers that together govern the shape, size and texture of our universe.
"Every single young person in this country should have the opportunity to appreciate and comprehend these aesthetics."
Last month, ministers unveiled proposals for a back-to-basics maths curriculum.
Under the plans, pupils will be expected to memorise their times tables up to 12 by age nine and multiply and divide fractions by age 11, as well as learn how to deal with decimals, percentages and long division.
The government also plans to make it a requirement for pupils who do not achieve at least a C in GCSE maths to continue studying the subject up to age 19, Mr Gibb said, as well as wider reforms to A-levels and GCSEs.
Shadow schools minister Kevin Brennan told the conference that all parties would like to see an increase in the numbers of students studying maths up to age 18.
More must be done to encourage pupils who get lower grades in GCSE maths to take additional courses in the subject, he said.
"We need to examine how we can incentivise these pupils to take some kind of additional courses, possibly leading to a new qualification that will encourage them to take maths, and indeed other core subjects such as English beyond 16."
He added: "I want to set out our thinking for those pupils who get a good grade at GCSE maths, but then don't go on to study A-level.
"Of those pupils who get a B or a C grade in GCSE maths, only 16% will go on to study AS-level maths. Of those who get an A at GCSE, the number increases to around 50%, and for A*, it is as high as 80%."
Mr Brennan said that Labour is examining the idea of creating a new course, between GCSE and A-level, for teenagers who want to continue studying maths, but do not think an A-level is right for them.