Union leaders are angry at plans to reorganise the allocation of customs officers across the South West.
Smugglers will cash in say unions
Under new proposals which could be rolled out across the country, customs officers at ports and airports in Devon, Cornwall and Dorset could be replaced by mobile units.
The public and commercial services union fears officers could be called upon to work anywhere in the region, or even as far afield as Dover and Gatwick.
It has been in talks with management and is mounting a campaign to draw attention to its concerns.
David Millar of the Public and Commercial Services Union, said the move would "open the back door" to smugglers.
North Cornwall MP Paul Tyler said: "Customs management is effectively hoisting a flag which says smugglers will get in with no problems in the South West.
"In terms of drugs it could be disastrous."
Customs and Excise say they want to increase the detection rate by targeting ports favoured by smugglers.
It says staff unwilling or unable to make the transition into mobile teams will be accommodated as far as possible in other jobs or vacancies in other government departments.