The 28-year-old man from Tilbury, England, entered his plea when appearing at the Central Criminal Court of England and Wales (Old Bailey) via video link.
Police said Hanga will appear in court for sentencing at a later date.
Earlier, on April 8, 25-year-old lorry driver Maurice Robinson from Craigavon in Northern Ireland pleaded guilty to 39 counts of manslaughter at the Old Bailey. He had previously pleaded guilty to conspiracy to assist unlawful immigration and acquiring criminal property at the same court on November 25 last year.
Four other men will stand trial at the Old Bailey in connection with this case in October.
Last October, the bodies of the Vietnamese nationals were discovered by emergency services on the back of a regiferated lorry at an industrial estate in Essex.
Among the 39 dead were ten teenagers, including two 15-year-old boys./
VNA/VNP
