The GHB seized is thought to have a street value of about �1m

Officers found 15 blocks of the solvent in its powder form during a raid in Craghead - enough to make thousands of doses of the drug.

GHB is linked to drug-assisted sexual assaults. It is colourless and odourless when diluted in drinks.

A woman in her 40s and a man in his 30s have been arrested on suspicion of importing and supplying class C drugs.

Det Sgt John Foreman of Durham Police, said GHB was "extremely dangerous".

He added: "Somebody can take it one time, but it can kill them the next. In date-rape cases, the intended purpose is to stupefy the victim so they have no recollection of the night before."

The GHB seized is thought to have a street value of about �1m. One diluted teaspoon of the powder is enough to make more than 100 doses of the drug.