LONDON -- The latest on the case of 39 people found dead in a truck in England (all times local):

6:10 p.m.

British police say they have arrested a fourth person in connection with the deaths of 39 people found in a truck in southeast England.

Essex Police deputy chief Pippa Mills says a 48-year-old man from Northern Ireland was arrested at England's Stansted Airport on Friday on suspicion of conspiracy to traffic people and conspiracy to manslaughter.

In addition, the 25-year-old truck driver, also from Northern Ireland, remains in custody, and a man and woman from northeast England have also been arrested.

Mills said the force would not "speculate" about the victims' nationalities, but said "this is now a developing picture." Police earlier had said that all the victims were believed to be Chinese citizens, but reports have emerged that some may have been from Vietnam.

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3:50 p.m.

The Vietnamese Embassy in London has confirmed that it has contacted police about a missing woman feared to be one of the 39 people found dead in a truck in southeastern England.

A spokesman for the embassy said Friday that it had been contacted by a family in Vietnam who claimed their daughter had been missing "since the lorry was found." The spokesman said: "We have contacted Essex Police and we are waiting for an answer."

after the bodies were found early Wednesday in an industrial park. Authorities began performing autopsies Friday on the remains of some truck victims as police try to piece together their identities.

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3:40 p.m.

The Associated Press has visited the address of a company in Bulgaria that the Bulgarian government says owns the truck in which 39 people were found dead in England. But residents of the building in the Black Sea port of Varna say it has never had any offices of foreign firms.

Bulgarian media have reported that the owner of the truck was a company named "Tomorrow Movements Today" registered in Varna by an Irish woman.

One man, who would only give his name as Stoyan, said he had lived in the building since 1991 and has never seen an office of a foreign company here.

It's common for companies from Western Europe to register their trucking companies in Bulgaria due to low taxes and easy registration procedures. Although there are no official statistics of the number of foreign cargo trucks with Bulgarian registration plates on European roads, experts believe they are in the hundreds.

-- by Petrova Valentina.

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12:55 p.m.

British police say they've arrested two more people in connection with the deaths of 39 people found in the back of a container truck in southeastern England.

Police say a man and a woman, both 38 and from Warrington in northwest England, have been arrested on suspicion of manslaughter and conspiracy to traffic people.

The 25-year-old driver of the truck remains in custody on suspicion of murder.

Essex police said the victims were believed to be from China. The truck was found Wednesday near a port in southeast England.

China's embassy in London, however, says Friday in a statement that police are still verifying the victims' identities and their nationalities had not yet been confirmed.

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4 a.m.

China is calling for joint efforts to counter human smuggling after the discovery in Britain of 39 dead people believed to be Chinese who stowed away in a shipping container.

Foreign ministry spokeswoman Hua Chunying told reporters at a daily briefing that China could not yet confirm the victims' nationalities or identities but was working in co-operation with local authorities.

Hua says "I think that no matter where these victims come from, this is a great tragedy which drew the attention of the international community to the issue of illegal immigration," she said.

Hua said Chinese authorities were also seeking information from police in Belgium, from where the shipping container in which the bodies were found was transported to England.

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LONDON -- British police arrested two more suspects Friday in connection with the deaths of 39 people found in the back of a container truck in southeastern England as the investigation into one of the country's worst human smuggling cases geared up.

Police said the man and the woman, both 38 and from northwestern England, were arrested on suspicion of manslaughter and conspiracy to traffic people. The 25-year-old driver of the truck remains in custody on suspicion of murder.

The new arrests came as police began the grim process of conducting post-mortem examinations of the dead on Friday. The remains of 11 people from the truck were transported Thursday by ambulance from the Port of Tilbury to a mortuary under police escort.

Essex Police said 31 men and eight women were found dead in the truck early Wednesday at an industrial park in Grays, a town 25 miles (40 kilometres) east of London.

Although U.K. police said they believed the dead were Chinese citizens, Chinese officials told reporters in Beijing the nationalities and identities of the victims had not yet been confirmed.

The Vietnamese Embassy in London confirmed Friday that it contacted police about a missing woman feared to be one of the dead. An embassy spokesman said it was contacted by a family in Vietnam who says their daughter had been missing since the truck was found.

Chinese Foreign Ministry spokeswoman Hua Chunying said China was working in co-operation with local authorities.

"No matter where these victims come from, this is a great tragedy which drew the attention of the international community to the issue of illegal immigration," she said. "The international community should further strengthen co-operation in this area, strengthen sharing of information and intelligence ... to prevent such tragedies from happening again."

Hua said Chinese authorities were also seeking information from police in Belgium, since the shipping container in which the bodies were found was sent to England from the Belgian port of Zeebrugge.

Human smuggling from China is believed to have fallen drastically in recent years amid the country's rapidly growing domestic economy. However, some Chinese, particularly those with lesser education, continue to be drawn to Europe and North America by the promise of much higher wages than they can earn at home, despite the considerable risks involved.

Parts of China, especially the southeastern province of Fujian, have long histories of sending migrants abroad.

The issue is a difficult one for China's ruling Communist Party, which is intensely sensitive about China's international image and has staked much of its legitimacy to rule on improving living standards for the bulk of China's 1.4 billion people.

In an editorial Friday, the party newspaper Global Times said authorities in Britain and elsewhere hadn't done enough to crack down on people smuggling.

"Such a serious humanitarian disaster occurred under the eyes of the British and Europeans," the newspaper said. "Britain and the related European countries have not met their responsibility for protecting these people from dying in such a manner."

British police believe the truck and container took separate journeys before ending up at the industrial park. They say the container travelled by ferry from Zeebrugge to Purfleet, England, where it arrived early Wednesday and was picked up by the truck driver and driven the few miles to Grays.

The truck cab, which is registered in Bulgaria to a company owned by an Irish woman, is believed to have travelled from Northern Ireland to Dublin, where it caught a ferry to Wales, then drove across Britain to pick up the container.

Global Trailer Rentals Ltd told Ireland's national broadcaster RTE the trailer it owns was leased Oct. 15 in County Monaghan, in Ireland, at a rate of 275 euros ($299) per week. The Dublin-based company said it will make the data from its tracking system available to investigators.

The company's directors told RTE it was "shell-shocked" at the news.

Groups of migrants have repeatedly landed on English shores using small boats to make the risky Channel crossing, and migrants are sometimes found in the back of cars and trucks that disembark from the massive ferries that link France and England.

But Wednesday's macabre find in an industrial park was a reminder that criminal gangs are still profiting from large-scale trafficking.

The tragedy recalls the deaths of 58 Chinese migrants who suffocated in a truck in Dover, England, in 2000 after a perilous, months-long journey from China's southern Fujian province. They were found stowed with a cargo of tomatoes after a ferry ride from Zeebrugge, the same Belgian port featured in the latest tragedy.

In February 2004, 21 Chinese migrants -- also from Fujian -- who were working as cockle-pickers in Britain drowned when they were caught by treacherous tides in Morecambe Bay in northwest England.

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Bodeen reported from Beijing. Raf Casert in Brussels and Shanshan Wang in Beijing contributed.