Police are investigating a suspected Irish people-smuggling ring after 39 migrants were found frozen to death in the back of a refrigerated lorry.

One of UK's biggest murder inquiries was launched on Wednesday after the bodies, including that of a teenager, were found dead in the truck on an Essex industrial estate.

The container carrying the people arrived at Purfleet, close to Tilbury Docks, from Zeebrugge, in Belgium, at 12.30am on Wednesday.

It left the docks at 1.05am on the back of the cab which had entered the UK via Holyhead from Dublin four days earlier.

Just 35 minutes later the police were alerted that the truck was on an industrial estate in nearby Grays, Essex and the bodies had been found inside.

The driver of the cab, named locally as Mo Robinson, 25, from County Armagh in Northern Ireland, was arrested on suspicion of murder.

Mr Robinson may have alerted the authorities himself, it emerged. Sources close to the investigation told the Telegraph that it is “very unlikely” that he knew about the plans to smuggle people across borders.

Temperatures in the refrigerated truck get as low as -25C and sources said the people are likely to have died from suspected hypothermia.