According to local finances, seven migrants were found in the rear of a cross-Channel lorry, which prompted emergency authorities to launch a quick inquiry.
The lorry is reported to have left Dieppe on Friday morning and arrived at the East Sussex port of Newhaven via the Seven Sisters passenger ferry.
On Friday, images from the site showed multiple ambulances in attendance in addition to Border Force and police.
Sussex police said: “A man has been arrested on suspicion of facilitating illegal entry to the UK, and a second man has been arrested for illegally entering the UK.
“The ambulance service has taken six further people to hospital for treatment.”
A South East Coast Ambulance spokesman said: “We were called at 9.40am this morning to an incident at Newhaven Ferry Port.
“A range of ambulance resources have attended, including our HART [Hazardous Area Response Teams], alongside other emergency service partners.”
Responding to media reports about the incident, Maria Caulfield, the MP for Lewes, which includes Newhaven, said online: “Very concerned about these reports. From my office in Newhaven we can see lots of activity opposite at the port and thanks to the emergency services responding.”
It is understood the lorry driver has been arrested on suspicion of facilitating illegal entry to the UK. Six migrants have been taken to hospital and one has been arrested for suspected illegal entry.
The Home Office do not believe any migrants have died but this is yet to be formally confirmed.
A Home Office spokesperson said: “Border Force are supporting emergency services in response to an incident at Newhaven Ferry Port.
“While the incident is ongoing, it would be inappropriate to comment further.”