The Home Office confirmed that proposals for "Border Force Special Volunteers" at small air and sea ports were being discussed.
They would be used to bolster Border Force staffing levels, in a similar vein to police community support officers.
However an MP whose constituency covers one of Britain's largest ports warned against creating a "Dad's Army-type set-up", due to the complexities of border security.
The Border Force carries out immigration and customs controls for people and goods entering the UK, and reports in the past have raised concerns over "poor" coverage of dozens of minor harbours and landing places.
A Home Office spokesman said: "Border Force is currently considering the potential benefits of a Border Force Special Volunteer force, and is in discussions with other law enforcement agencies such as local police to understand how they use volunteers in addition to their existing workforce."
An inspection by the department published earlier this year of 62 ports, wharves, marinas and jetties on the east coast that were normally unmanned found Border Force officers had not been to 27 of the sites during the 15 months from April 2015 to June 2016.
The assessment said one of the risks of long periods of non-attendance by Border Force at some locations is "there is no visible deterrent to anyone prepared to risk using these spots to land illegal migrants or contraband".
In a separate report, former independent reviewer of terrorism legislation David Anderson QC also flagged up coverage of smaller south and east coast ports, marinas and landing places, saying it is "conceivable" they might be an option for returning foreign fighters or other terrorists.
The Home Office said it uses a mix of expert officers, technology, data and intelligence to keep UK borders secure and has stopped tens of thousands of illegal attempts to enter the country.
A spokesman said volunteers would not be used by Immigration Enforcement, but added: "We're committed to ensuring that Border Force has the resources it needs to keep the UK safe and we will never compromise the security of our borders."
Dover MP Charlie Elphicke told the Mail on Sunday: "Border security is a skilled job, which takes many years of training. I would urge great caution before seeking to adopt a model like that used by the police, with special constables. We can't have a Dad's Army-type of set-up."