Charges brought against 69 migrants who were arrested after a fishing boat was intercepted off the coast of East Anglia have been dropped.
The Albanian nationals had been charged by Home Office officials with entering the UK illegally.
Three men who were on the vessel have been charged with people-smuggling offences.
The Home Office said it was "disappointed" the proceedings have been discontinued.
British officials had accompanied the boat into Harwich harbour in Essex last month after it was intercepted off Great Yarmouth, Norfolk.
The vessel had set off from Ostend, Belgium.
Five of the migrants had already been given eight-week prison sentences after admitting at Ipswich Magistrates' Court to knowingly entering the UK without leave.
The Crown Prosecution Service said: "We have authorised charges against three people for facilitating illegal entry to the UK.
"After careful consideration, we have decided our legal tests for prosecution were not met in relation to the 69 passengers.
"Proceedings commenced by Immigration Enforcement will therefore be discontinued and any convictions returned to court."
The Home Office said the "successful Border Force operation" had resulted in "the seizure of a valuable fishing vessel".
A spokesperson said: "We are disappointed that the proceedings against the 69 people charged with illegal entry will be discontinued and we are working with the CPS urgently to resolve the issues raised by this case.
"The immigration cases will be dealt with as quickly as possible and removal action will be pursued against anyone found to have no right to remain in the UK.
"Knowingly entering the UK without leave is a criminal offence and anyone who has committed such an offence should be prepared to face prosecution."