Cocaine with a street value of £3m was seized by police and Border Force officers
National Crime Agency (NCA) and Border Force officers discovered 36kg of the drug inside what is believed to be a purpose built hide in the truck.
The lorry arrived in Dover from France on Thursday night, the NCA said.
The driver, a 50-year-old man from Co Armagh was arrested on suspicion of conspiring to import Class A drugs.
Shortly afterwards NCA officers arrested a 56-year-old man from Kingswood in Kent.
A 40-year-old, from River near Dover, was detained at a haulage yard in the town on Friday, also on suspicion of conspiring to import Class A drugs.
All three men remain in custody and will be questioned by NCA investigators.
The PSNI carried out searches at properties in Co Derry and Co Armagh.
NCA regional head of investigations Gerry McLean said: “This was a significant seizure of Class A drugs which would have generated a large amount of profit for criminals involved in drug supply.”
Dave Smith, Border Force regional director, said: “We will continue to work with the NCA to bring drugs smugglers to justice.”