Police were called shortly after 8am this morning by a member of public reporting concerns for the welfare of a number of people, in the back of a lorry, on Quartremaine Road.
Thirty-one immigrants were found inside the lorry.
The lorry has the name Ricardo Paul on it. Border Force are at the scene.
An official spokesman for Hampshire police said: '˜We were called at 8.07am by a member of the public reporting concerns for the welfare of a number of people in the back of a lorry.
'˜Officers are currently with the lorry on Quartremaine Road and are making enquiries.'
Ronan Kehoe, 40, is carrying out steel work at the '˜new police station' down the road.
He said: '˜When I walked past I saw the lorry, lots of police cars, and as I went further I saw it was immigrants who had been found.
'˜It's quite shocking. I've been working on this job since the second week of January and this is the first time I have seen anything like this - it's very surprising.'
Arron Brown, 25, is working with him. He added:Â '˜This is mental, I've never seen anything like it.
'˜32 is a lot of people to be coming here.
'˜I've been on this job for two months and I didn't even know this sort of thing happens.'
A passer-by, who wishes to remain anonymous, said the incident looks like '˜a massive police operation'.Â