A large quantity of drugs have been found buried on the site of Creamfields.
The annual festival will return to the Daresbury Estate in Cheshire for the Bank Holiday weekend with more than 80,000 music fans expected to attend this year.
Calvin Harris, Fatboy Slim and Armand Van Helden are among those who will headline the event, which has been held at the site for the past 20 years.
However police unearthed over 200 canisters of nitrous oxide and large bags containing ecstasy, MDMA and ketamine tablets concealed underground.
Further searches of the site will continue in the run-up to Creamfields as Cheshire Police attempts to make the event as save as possible for festival goers.
Superintendent Andy Blizard said: “Every year, we remind those attending Creamfields that there is a zero-tolerance policy regarding drugs.
“Every year, we encounter a number of brazen individuals who think that they can outsmart us by concealing drugs from view or burying them at the site months in advance.
“Our specialist search teams have spent a considerable amount of time combing the grounds of the Creamfields site ahead of the festival opening later this week.
“We fully expect to find further quantities as our searches continue, leaving many of those who chose to bury these items very much disappointed to find them no longer where they left them when they arrive at the festival to dig them back up.
“Anyone who has buried a rucksack or holdall bag at the site and would like it back is asked to get in contact with us.
“Officers have already begun conducting enquiries to identify their owners, and we look forward to speaking to them soon.”