Explosives experts from the Army were called to the scene on Friday morning, and police said a cordon was in place “for the safety of the public”.
The “suspicious” vehicle was stopped at 10.30am on Friday, at the Channel Tunnel entrance in Cheriton, and the terminal was closed.
LeShuttle - the service that transports vehicles throught the tunnel - said travel would be “severely disrupted” throughout Friday afternoon due to the “rare” incident.
“A man has been detained in connection with the incident and enquiries are ongoing,” said a Kent Police spokesperson.
Police confirmed the incident was not being linked to the search for missing terror suspect Daniel Abed Khalife, who escaped HMP Wandsworth prison on Wednesday.
LeShuttle posted on X, formerly known as Twitter, on Friday afternoon: “Due to a police incident access to our site is unavailable. Incidents of this nature are extremely rare and we’re grateful for your patience.
“As a consequence of this incident, travel will be severely disrupted throughout the afternoon please prepare to modify your travel plans.”
Meanwhile enhanced security checks are being carried out at UK ports and airports as police continue to hunt 21-year-old former solider Daniel Khalife.
The M20 coastbound carriageway approaching the Port of Dover, between Junctions 8 and 9, remained closed on Friday due to delays caused by the enhanced checks.
The closure allows freight bound for the continent to queue on the empty section of motorway in order to keep any disruption to Kent’s wider road network to a minimum.