Holdalls containing hundreds of kilos of powder were discovered in the sea off St Aldhelm’s point and Durdle Door and a further quantity has washed up on a beach on the Isle of Wight.

The initial find was made on Monday 2 October by a fisherman who alerted Dorset Police. The packages are currently being examined to confirm their contents and quantity.

The investigation is being supported by Border Force, Dorset Police and Hampshire Police.

“We believe this a significant amount of class A drugs which would have originated in South America,” said Tracey Lake, NCA senior investigating officer. “A loss of a consignment of this size would represent a significant hit to the criminal networks involved.

“Our investigation is being assisted by both Dorset and Hampshire Police as well as Border Force. Any additional suspect packages encountered by members of the public should be reported to the relevant police force.”

Temporary deputy chief constable Rachel Farrell, of Dorset Police, said: “Officers from our marine team, supported by colleagues from across the Force and HM Coastguard have been working tirelessly with the NCA and Border Force to recover these suspect packages.

“We remain committed to joining forces with our partner agencies to relentlessly pursue criminals and organised gangs suspected of being involved in drug supply offences so that we can keep the public safe.”

Hampshire and Isle of Wight Constabulary’s ACC Stuart Murray said the force is supporting the on-going investigation with searches across West Wight, after a number of packages were discovered by a group out litter picking.

“We would ask anyone who finds any suspicious bags or packages on the coastline of Hampshire and the Island to get in touch with us immediately.”

Hampshire police officers would like to make contact with a member of the litter-picking group – a man in his 60s – as they continue to speak with everyone in the vicinity on the morning of the find. He is of slim build, around 5ft 6ins tall and had short grey hair, with a birthmark on the right side of his mouth.

Anyone who locates any suspicious package should call 999. Do not touch the package, but contact the police immediately.