Two people have been arrested on suspicion of conspiring to smuggle drugs into the local prison.
A teenage boy, 17, and woman, 22, were arrested for drug crimes while on the way to High Down prison on the outskirts of Banstead.
Officers stopped and searched their vehicle as they travelled along High Down Lane on Saturday.
The pair, from London, were arrested on suspicion of possession with intent to supply class A drugs and conspiring to smuggle them into prison.
Sgt Gary Pickett, from Epsom and Ewell police, said: "This is part of an ongoing operation involving local officers, units from the dog section and prison staff working together to crack down on drugs offences at the site."
The teenager and woman have been released on bail until June 22 as the investigation continues.
Anyone with information or suspicions about drug dealing in their area should call police on 101.
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