LONDON (Reuters) - The so-called club drug ecstasy is more likely than other stimulants like speed or crystal meth to kill young, healthy people who are not known as regular drug users, British researchers said on Friday.

A study of stimulant-deaths in Britain between 1997 and 2007 found that those who died after taking ecstasy were mainly younger and healthier than those who died after taking amphetamines.

Fabrizio Schifano of the University of Hertfordshire, who led the study, said his results were worrying because they appeared to show young people are particularly vulnerable to ecstasy -- and this age group is the most likely to take it.

This is a big public health concern, he said in a telephone interview.

Schifano used data from the National Programme on Substance Abuse Deaths database and the British Crime Survey. He found 832 people died from taking amphetamines and methylamphetamines, such as speed and crystal meth, over the 11 year study period, while 605 deaths were related to ecstasy.

Deaths from ecstasy were more common in victims who were young, healthy, and less likely to be known as drug users, he wrote in the study in the Neuropsychobiology journal.

Schifano said the results suggested young people aged between 16 to 24 seem to suffer extreme consequences after excessive intake of ecstasy, but it was not clear why.

Ecstasy and amphetamines are very similar -- they are part of the same pharmacological group, Schifano said. But ecstasy does seem to show an intrinsic toxicity that is higher than that of amphetamines.

Schifano said it may be that young peoples' brains, which are still developing at the age of 16 and 17, are more vulnerable to the effects of the drug.

Ecstasy is currently ranked in Britain as one of the most dangerous Class A drugs, alongside heroin and cocaine.

(Editing by Paul Casciato )

United kingdom Medicine