Police in Leicestershire have seized a quantity of Class A drugs with a street value of at least £5m.
Officers raided two vehicles near the junction of the M1 and M6 shortly after 0800 BST on Thursday.
A police spokesman said it is believed to be the largest haul of Class A drugs ever found in Leicestershire.
Two men have been arrested and are currently being interviewed by detectives.
Leicestershire Constabulary is liaising with other forces in the UK and abroad as part of its investigation.
Det Ch Insp Neil Castle said: "From my knowledge, this is the largest haul of Class A drugs recovered in Leicestershire.
"The operation involved Police Community Support Officers, local beat officers and specialist crime investigation officers all working closely together."