A potent new variant of the drug ecstacy is being sold in clubs across the country, police forces have been warned.

In response to the threat from the hallucinogenic substance, called 2C-i, the National Criminal Intelligence Service has issued an assessment of the dangers of the drug to police forces.

Between May and August this year a total of 125 of the small white pills, which are marked with an "i", were seized in nine separate hauls including one in Bedfordshire.

The largest seizure of 65 tablets was at this summer's Glastonbury festival.

They are believed to have been smuggled in from Europe - possibly from Denmark.

The drug may appeal to dealers because - unlike tabs of ecstacy, now selling for as little as £1 each - 2C-i pills can fetch up to £10 each.

A police source said: "According to people who have taken it, it's very strong and very powerful.

"If someone unwittingly takes this drug to go clubbing and then starts hallucinating and thinking they can fly then, obviously, that could end badly."

Experimenting with such drugs is always risky, an NCIS source warned clubbers.

"People who become involved in synthetic drugs risk their health simply because there is no regulation of how the drugs are manufactured.

"Users may not be aware of the side-effects of commonly-used ecstasy variants with potentially tragic consequences."

Though the drug is currently believed to be smuggled in from abroad, the police source indicated it could be domestically manufactured.

"The chemicals to make this are available and it can be made pretty much anywhere."