27 July 2012 Last updated at 10:55 ET

Police mephedrone warning after death in Pembroke Dock

Police say mephedrone can cause heart attacks, seizures, sweating and paranoia

Police have warned about the dangers of a formerly legal drug following the death of a 26-year-old man at a property in Pembroke Dock.

The dead man, and a second man who was taken to hospital, are believed to have taken mephedrone, known as meow meow.

The cause of death is not yet known but toxicology tests will take place.

Dyfed-Powys Police have warned about the dangers of the drug and say it can cause heart attacks.

It has been linked with several UK deaths.

"There are some serious side effects to using meow meow," said Det Insp Anthony Griffiths.

"These can include heart attacks, seizures, sweating and paranoia."

It has been illegal to possess or supply mephedrone since April 2010, and police say being caught with it could mean a jail sentence of up to five years.