The House of Commons has been told that two unaccompanied children were among 68 migrants discovered in containers at Harwich docks.
The Home Office minister James Brokenshire said they were now in the care of Essex Social Services.
Parliament was also told that 15 of the migrants had already been deported.
Amongst the 68 migrants discovered arriving in Harwich, there were 2 unaccompanied minors who are now in care of Essex Social Services
Home Office Minister says of the 68 migrants discovered arriving in Harwich on Thursday night , 15 have already been deported
The nationalities of the 68 migrants arriving at Harwich on Thursday, 35 Afghan, 22 Chinese, 10 Vietnamese and 1 Russian
Click below to watch a report by ITV News Anglia Political Correspondent Emma Hutchinson
Four Polish lorry drivers arrested after 68 suspected illegal immigrants were found locked in their vehicles have been released on bail.
They were taken in to custody after the 35 Afghan nationals, 22 Chinese nationals, 10 Vietnamese and one Russian passenger were discovered at Harwich International Port in Essex at about 10pm on Thursday.
But after almost two days of being questioned by authorities, the drivers who were arrested on suspicion of facilitating illegal immigration were bailed until July 2.
The incident was described as one of the "biggest single finds of clandestines coming into the UK" by Bernard Jenkin, MP for Harwich and North Essex.
Fifteen of those discovered hiding amid Polish washing machines were children.
In total seven people - including two pregnant women - were taken to hospital to be checked before being released into the care of Border Force officials.
A Home Office spokesman confirmed that 53 adults and 15 children were found during a "proactive search".
The 68 individuals arrived at the port at 7.45pm on lorries that had boarded the Stena Hollandica ferry which sailed from the Hook of Holland at 2.25pm.
Staff and volunteers from the British Red Cross were providing practical and emotional support including blankets, food and hygiene packs to those affected.
Leigh Daynes, executive director of Doctors of the World UK which provides medical aid to undocumented migrants throughout Europe, said: "Over an dover we see migrants who have risked life and limb to cross Europe.
"With few safe routes to enter the continent, many more will continue to take dehumanising and perilous journeys like this."
Officers from the British Red Cross are supporting the 68 people found inside lorries at Harwich International Port, as Border Force officials continue their investigations.
The charity's volunteers have given the 53 adults and 15 children provisions including blankets, food and hygiene packs, as well as providing emotional support.
The suspected illegal immigrants were found locked inside four separate lorries during routine checks yesterday evening.
Ferry firm Stena Line has confirmed that 68 suspected illegal immigrants discovered at Harwich International Port were found inside lorries travelling on one of its ships.
A Stena Line spokeswoman described the Stena Hollandica as a "supership" that carries both passengers and freight.
Stena Line can confirm that four different lorries carrying 68 clandestines were stopped by Border Force at Harwich International Port last night as they disembarked from the Stena Hollandica.
The ship had sailed from the Hook of Holland to Harwich, leaving the Hook of Holland at 1415 and arriving in Harwich at 1945 on Thursday 4 June.
Following earlier reports from East of England Ambulance Service that the 68 were found inside one container, the Home Office confirmed that they were discovered "during a proactive search of four lorries".
Fifteen children and two pregnant women were among the 68 suspected illegal immigrants discovered by Border officials at Harwich International Port.
The suspected stowaways - 35 Afghan nationals, 22 Chinese nationals, 10 people from Vietnam and one Russian - were found during a "proactive" search of four lorries, a Home Office spokesperson said.
We can confirm Border Force officers discovered 53 adults and 15 children during a proactive search of four lorries which had arrived at Harwich port from Holland on Thursday evening.
Seven of those discovered were taken to hospital as a precaution, before being released. All 68 individuals are now in the care of Border Force.
Four Polish nationals who were driving the vehicles were arrested on suspicion of facilitating illegal immigration.
They are being questioned by the Home Office’s criminal investigations team at separate police stations.
Four Polish lorry drivers have been arrested on suspicion of immigration offences after Border Force officers found 53 adults and 15 children during a search of lorries which had arrived at Harwich port from Holland, the Home Office said.
Emergency services have rescued 68 people from a locked container in an Essex port. Seven people were taken to hospital.
The East of England Ambulance Service went to Harwich Port after a 999 call last night.
The patients were suffering from abdominal and chest pains and were feeling faint. They were taken to Colchester General Hospital.
Another 61 people have been released to UK Border Agency officials.
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Lifeboats were called out to a container ship off the coast of Essex which was left drifting in a major shipping lane.
The 260 metre-long ANL Warringa was on its way to Hamburg from Tilbury when it lost power 30 miles off the Essex coast.
Lifeboats from Harwich, and Walton and Frinton stayed with the ship until 11pm last night as a commercial tug from Holland pulled the ship to its destination.