A truck driver has pleaded guilty to 39 counts of manslaughter related to the deaths of Vietnamese people found in a shipping container in southeast England last year.

Maurice Robinson, a 25-year-old from Craigavon in Northern Ireland, entered the plea at Central London Criminal Court where he appeared via video link alongside four co-defendants.

The bodies of the 31 men and 8 women were discovered in a refrigerated trailer in the town of Grays, east of London, shortly after arriving on a ferry from Zeebrugge in Belgium.

Police investigating the case found the victims were all from Vietnam and ranged in age from 15 to 44 and are believed to have paid people traffickers to smuggle them into England.

Most of the victims were from Nghe An and Ha Tinh provinces in north-central Vietnam, where poor job prospects, environmental disasters and the promise of financial reward fuel migration.

A vigil had previously been held for the victims. Photo: AP/Kirsty Wigglesworth

Autopsies concluded that the likely cause of death of the 39 Vietnamese people was a combination of oxygen deprivation and hyperthermia in an enclosed space.

Among the dead were 10 teenagers.

• Read: Essex truck victims: Who and what made Vietnamese villagers leave home?

Of the other defendants Gheorghe Nica, 43, denied 39 counts of manslaughter.

Romanian national Alexandru-Ovidiu Hanga, 27, denied a charge of conspiracy to assist unlawful immigration.

Christopher Kennedy, 23, of County Armagh, Northern Ireland, has previously denied conspiracy to assist unlawful immigration.

Valentin Calota, 37, of Birmingham, was not asked to enter a plea to the charge of conspiring to assist unlawful immigration.

Mr Robinson also admitted to one charge of transferring criminal property, but denied a charge of transferring criminal property.

-with Reuters