About 360kg (793lbs) of cocaine that has washed up on Hopton beach, near Great Yarmouth and a beach near Caister.
A member of the public contacted Norfolk Police having discovered a number of holdalls on Hopton Beach.
The seizure was referred to the National Crime Agency and officers continue to search the area.
More on this and other stories at BBC Local Live: Norfolk
Matthew Rivers, from the NCA's border investigation team, said: "We are now working with Border Force, the Coastguard Agency and Norfolk Police to try and establish how the bags ended up where they did, however it is extremely unlikely that this was their intended destination.
"This is obviously a substantial seizure of class A drugs and its loss will represent a major blow to the organised criminals involved."
Supt Dave Buckley, from Norfolk Constabulary, said: "Whilst we believe we have recovered all the packages, should any member of the public find one they are urged to contact Norfolk Constabulary immediately.
"We will have extra officers in the area to monitor the situation."
Cocaine valued at up to £50m has been washed up on beaches in Norfolk, the National Crime Agency says.