"The British police are investigating the incident and are unable to confirm the identities of the victims, they have not provided us with any additional information," China’s Foreign Ministry spokesman Geng Shuang said at a regular press briefing Monday.

The Chinese embassy in Vietnam is maintaining close contact with relevant Vietnamese agencies over this incident, he said.

Geng described reports that the victims had Chinese passports as "speculation."

He said he hoped concerned parties make remarks based on facts, instead of "subjective guesswork from first impressions," the Washington Post reported.

On Monday, British authorities sent the files of four of the 39 victims in the U.K. tragedy to Vietnam for identity verification.

Britain’s ambassador to Vietnam Gareth Ward met Monday with Vietnamese officials to discuss cooperation in identifying the 39 bodies found in the truck in southeastern England.

Ward also told Vietnam’s Ministry of Public Security that Britain still has not confirmed the identities or nationalities of the victims.

"This identification process will take time to ensure the dignity of the victims, to guarantee forensic accuracy, and to secure information for the ongoing investigation," he said in a statement released Monday.

As of Sunday, 24 families in the central province of Nghe An and neighboring Ha Tinh Province had reported relatives missing in the U.K. and other countries in Europe.

The Ministry of Public Security has said it is investigating possible involvement of individuals or groups who help Vietnamese emigrate illegally.

Prime Minister Nguyen Xuan Phuc on Saturday ordered a probe into the trafficking of Vietnamese citizens.

On October 23, U.K. emergency services discovered the bodies of 38 adults and one teenager, suspected immigrants, in a refrigerated container truck at the Waterglade Industrial Park in Grays, Essex County, east of London.

Police initially believed all of the dead were Chinese nationals, but the force later said "this is now a developing picture" amid reports several may be Vietnamese.

Maurice Robinson, the 25-year-old truck driver, of Craigavon in Northern Ireland, has been charged with 39 counts of manslaughter and other offences including conspiracy to traffic people.

Three other people arrested in connection with the investigation have been released on bail until November 11-13.

Vietnam reported 490 human trafficking victims in 2018. The U.S.'s Trafficking in Persons Report 2019 said the Vietnamese government has not fully met the minimum standards for the elimination of trafficking but is making significant efforts to do so.

Some 70 percent of Vietnamese trafficking cases in the United Kingdom between 2009 and 2016 were linked to labor exploitation, with young people forced to work in cannabis production and nail salons, according to a British government report last year.

A March report by the Pacific Links Foundation, a U.S.-based anti-trafficking organization, had identified Nghe An, one of Vietnam's poorest provinces, as home to many victims of human trafficking who end up in Europe.