Six migrants were rushed to hospital after being discovered in a refrigerated lorry on a ferry.
Around 20 ambulances and police cars raced to Newhaven port after the alarm was raised on the Seven Sisters crossing from Dieppe.
Two of the migrants are said to be seriously ill. Extraordinary pictures showed paramedics treating the stowaways within the port before they were taken to hospital.
The Daily Express understands more migrants are attempting to reach the UK by climbing into the backs of lorries.
This is believed to down to intensified efforts to disrupt people smugglers from forcing dozens of people into small boats bound for Britain.
Law enforcement agencies across Europe are trying to prevent boats – many of which are made in China or Turkey – and equipment such as engines from reaching France.
In 2019, 39 migrants were found dead in a lorry in Essex. The bodies of the Vietnamese nationals, who were aged between 15 and 44, were discovered on 22 October 2019 after they were transported in an airtight container from Zeebrugge in Belgium to Purfleet in Essex.
Gang ringleader Gheorghe Nica, a 46-year-old Romanian, was found guilty of the manslaughter of the victims and jailed for 27 years in 2021.
Sussex Police said a man has been arrested on suspicion of facilitating illegal entry to the UK and a second man was arrested for illegally entering the UK after the discovery in Newhaven.
Martin Sinnock, 70, whose home overlooks the entrance to Newhaven Harbour, said he saw “a lot of activity” and a “large” emergency services presence including a helicopter landing on the quayside shortly after the ferry arrived, telling PA he was “deeply sad” to hear migrants were inside the vehicle.
Sussex Police said: “We are currently supporting Border Force, who are the lead agency, and other emergency services after a number of people were found on a lorry on a boat in Newhaven Port.
“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 force spokesman confirmed the boat referred to in its statement was a ferry.
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.”
