GRAYS (England) • British police found the bodies of 39 people inside a truck, believed to have travelled from Bulgaria, at an industrial estate near London yesterday, and said they had arrested the driver on suspicion of murder.

The discovery of the bodies - 38 adults and one teenager - was made in the early hours after emergency services were alerted to people in a container truck on a gritty industrial site in Grays, about 32km east of central London.

The truck was thought to have entered Britain at Holyhead, a North Wales port that is a major entry point for traffic from Ireland, last Saturday and to have started its journey in Bulgaria, police said. The driver of the truck, a 25-year-old man from Northern Ireland, is in custody.

British Prime Minister Boris Johnson said he was appalled by the news and was receiving regular updates about the investigation.

"We know that this trade is going on - all such traders in human beings should be hunted down and brought to justice," he said.

All those in the container were pronounced dead at the scene after the emergency services were called to the Waterglade Industrial Park, not far from docks on the River Thames.

Bulgaria's Foreign Ministry said it has been in contact with the British authorities over the incident. "At present, it has not yet been confirmed whether the truck has a Bulgarian registration," a foreign ministry spokesman said. "There is also no indication of the nationality of the human bodies found in the truck. British police have warned that the identification of the bodies will take a long time."

Irish Prime Minister Leo Varadkar said the Irish authorities would carry out any investigations necessary if it was established that the truck had passed through Ireland.

Police officers in forensic suits were inspecting a large white container on a red truck next to warehouses at the site. Police sealed off the surrounding area of the estate with large green barriers as they carried out their investigation.

"At this stage, we have not identified where the victims are from or their identities and we anticipate this could be a lengthy process," Essex Police deputy chief constable Pippa Mills told reporters. "This is an absolute tragedy."

Ms Mills said the first priority is finding out the victims' identities, while a key line of inquiry is determining the truck's route from Bulgaria to Ireland and then Britain.

For years, illegal immigrants have attempted to reach Britain stowed away in the back of trucks, often seeking to reach Britain from the European mainland.

In Britain's biggest illegal immigrant tragedy, Customs officials found the bodies of 58 Chinese crammed into a tomato truck at the southern port of Dover in 2000.

Mr Jeremy Corbyn, the leader of the opposition Labour Party, said the latest deaths were an unbelievable human tragedy that needed answers. "Can we just think for a moment of what it must have been like for those 39 people, obviously in a desperate and dangerous situation, for their lives to end, suffocated to death in a container," he said.

REUTERS