Police closed both carriageways of the M27 between Hamble Bridge and just past Junction 9 at Fareham after reports that four men, believed to be illegal immigrants, were seen running from the back of a lorry.
The incident happened at 11.56am and police were alerted by the driver of the lorry who had had travelled from Italy and was delivering goods in Segensworth.
Air support was called in from Bournemouth to help locate the men who had run onto the motorway.
Police on the ground formed a rolling roadblock to keep traffic back while the road ahead was closed.
Three of the four men were caught and arrested shortly before 1pm. The oustanding man is described as being of Chinese extraction and wearing dark clothing.
The road was reopened shortly afterward.
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