Border Force, police and paramedics were called to the scene as a major operation was launched.

Local newspaper The Argus said the migrants were found in the back of a refrigerated lorry crossing from Dieppe in France.

It said authorities were alerted before the ferry docked.

South East Coast Ambulance said it was called at 9.40am and "a range of ambulance resources" deployed.

One man has been arrested on suspicion of facilitating illegal entry to the UK, and a second for illegally entering the UK, said Sussex Police.

In 2019, 39 migrants were found dead in a lorry in Essex but there are so far no reports of deaths in today's incident.

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The Home Office said the Border Force was supporting emergency services but that "while the incident is ongoing, it would be inappropriate to comment further".

Local Conservative MP Maria Caulfield said she was "very concerned".

"From my office in Newhaven we can see lots of activity opposite at the port and thanks to the emergency services responding," she said.