AT least three of the 39 people found dead in a lorry trailer in West Thurrock may have been from Vietnam reports the BBC.
The BBC knows of three Vietnamese people whose relatives are worried they may have been in the trailer.
Pham Thi Tra My, 26, has not been heard from since she sent urgent messages on Tuesday saying she could not breathe.
Two people have been arrested on suspicion of manslaughter and the lorry driver remains in custody on suspicion of murder.
Ms Tra My’s brother, Pham Ngoc Tuan, says she had paid £30,000 to people smugglers and her last-known location had been Belgium.
The smugglers are understood to have returned money to families of suspected victims.
The last message they received from her was at 22:30 BST on Tuesday – two hours before the trailer arrived at the Purfleet terminal from Zeebrugge in Belgium.
Her brother told the BBC: “My sister went missing on 23 October on the way from Vietnam to the UK and we couldn’t contact her. We are concerned she may be in that trailer.
“We are asking the British police to help investigate so that my sister can be returned to the family.”
Ms Tra My’s family have shared the last text messages she sent to her parents.
They read: “I am really, really sorry, Mum and Dad, my trip to a foreign land has failed,” she wrote.
“I am dying, I can’t breathe. I love you very much Mum and Dad. I am sorry, Mother.”
Ms Tra My’s brother told the BBC her journey to the UK had begun on 3 October. She had told the family not to contact her because “the organisers” did not allow her to receive calls.
The bodies were discovered in the early hours of Wednesday
“She flew to China and stayed there for a couple days, then left for France,” he said.
“She called us when she reached each destination. The first attempt she made to cross the border to the UK was 19 October, but she got caught and turned back. I don’t know for sure from which port.”
The BBC has passed details of Ms Tra My, who is from Nghen town in Can Loc district of Ha Tinh province area of Vietnam, to Essex Police.
The BBC also knows of two other Vietnamese nationals who are missing – a 26-year-old man and a 19-year-old woman.
The brother of the 19-year-old said his sister called him at 07:20 Belgian local time (06:20 BST) on Tuesday, saying she was getting into a container and was turning off her phone to avoid detection.
He has not heard from her since.
He said a people smuggler returned money to the family overnight, and the family of the 26-year-old who she was travelling with also received money back.
A spokesman from the Vietnamese Embassy in the UK confirmed they were in contact with Essex Police in regard to Ms Tra My.