Until now, figures on heroin addiction among children were based on research collated in just two cities, Glasgow and Newcastle upon Tyne, where 90 heroin addicts under 13 were discovered.
But new government figures based on a nationwide survey, show that the problem is much more widespread than originally thought.
Doctors said the figure showed that heroin was a ticking "health time bomb" and parents called for urgent action by the Government.
Gaille McCann, a spokeswoman for Mothers Against Drugs, said: "They keep trying to reassure us that there isn't a crisis but they need to stop pretending and act quickly before the situation gets out of control."
Paul Skett, an addiction expert from Glasgow University, warned that heroin abuse could cause serious long-term damage to children's health. "Heroin affects the brain, hormonal and sexual development which means children won't develop properly and girls might not be able to have children when they are older," Dr Skett said.
The Government findings, from the study Smoking, Drinking and Drug Use Among Young People in England in 2004, says that in each year since 2000 1 per cent of all children used heroin at least once.
More than 9700 children aged 11 to 15 were interviewed. A similar survey was conducted in Scotland, where the same percentage of heroin users was found among 7000 schoolchildren.
Elizabeth Fuller, the lead statistician on the government survey, said that the figure was rounded up from 0.7 per cent but margins of error meant that the figure could be 0.5 per cent or 0.9 per cent - putting the nationwide number of children taking heroin at between 19,500 and 35,100.
However, Professor Neil McKeganey, a narcotics expert from Glasgow University, said the figure could be much higher than 35,000 and would continue to rise.
"Around 300,000 children growing up in the UK have one or both parents addicted to heroin. These children assume heroin use is quite normal," he said.
Andrew Lansley, the British shadow health secretary called for effective measures to make young people awareness of the risks.
A Department of Health spokesman said they had made sure that all schools receive guidance on solvents, drugs and alcohol.
Telegraph, LondonLast Mod: 20 Eylül 2018, 18:16