There are four times as many schoolchildren caring for disabled relatives as officially recognised, a survey has revealed.
Statistics published by the BBC show the UK has a "hidden army" of hundreds of thousands of young people responsible for the care of other family members.
One in 12 of schoolchildren questioned in the study said they had caring roles, helping relatives with tasks such as dressing, washing or bathing.
If the survey - which analysed data collected from 4,029 pupils at 10 secondary schools - reflects the UK as a whole, it is estimated there could be around 700,000 young carers.
The 2001 Census only identified 175,000, but this was previously described as a vast underestimate by charity groups.
Children's Minister Sarah Teather told the BBC the research showed the reality of what was really going on with young carers.
"It is shocking to see that they don't get the support they need or the recognition they deserve," she said.
Professor Saul Becker, head of the school of sociology and social policy at the University of Nottingham, was part of the team who designed the study.
He said the figures pointed to a "hidden army" of UK young carers and were a "wake-up call" to governments and carers' organisations.
Maggie Atkinson, Children's Commissioner for England, said: "Young carers in the UK are too often caught in the middle of a well-meaning muddle, missing out on vital support and services that can help them.
"For young carers who are still at school, poor or unco-ordinated support from the statutory sector can result in them missing out on the opportunities enjoyed by other children, which can blight their life chances as adults."
Ms Teather said the Government will launch a new strategy for carers later this year.
The National Young Carers Coalition said the figures came as "no surprise".
A spokesman said: "We always knew that the census figures were a vast underestimate.
"This is because it asked parents to complete the survey on behalf of their children, and also made no mention of more stigmatised conditions, such as mental health, substance misuse or HIV/Aids, which people are often fearful of declaring.
"And yet, despite this staggering increase in numbers, there will be a significant decrease in services to support them and their families."
He spokesman added: "Young carers need to be identified and supported early before caring causes damage to their health and wellbeing.
"Often just a small amount of help, put into place early enough, can significantly reduce a caring role and help young carers to cope.
"With cuts to local services, social workers and health professionals will be less able to act preventatively, and will be forced instead to support those young carers (and their families) who are already in crisis and who are deeply entrenched in inappropriate caring roles."Reuse content