One woman and seven men from Africa and a lorry driver have been arrested and handed over to the immigration authorities, police have confirmed.
Sussex Police said a woman, aged 28, and seven men, aged between 22 and 40, were arrested on suspicion of breaching UK immigration laws after a lorry was stopped and searched on the A27 on Wednesday morning.
After being questioned by Sussex Police they were handed over to immigration authorities.
The driver of the Italian-registered lorry, a 54-year-old man, was also arrested on suspicion of acting to facilitate a breach of UK immigration laws but was later released.
The large articulated lorry was stopped by police between Tangmere and Chichester.
According to Sussex Police, another driver spotted the lorry near Arundel railway station and thought there was someone trying to get out.
Suspecting illegal activity, he called police around 9.30am and tailed the lorry from Arundel.
Police were waiting at the Tangmere roundabout and took over, getting the lorry to pull over in a layby just after the A285 junction.
A number of people whom the police believe to be illegal immigrants were found on board.