Inquests will be opened into the deaths of the 39 Vietnamese migrants whose bodies were discovered in a refrigerated lorry in Essex last year, it has been confirmed.

The Guardian reported earlier on Tuesday that bereaved families and campaigners in the UK have called for inquests to be held into the deaths. A letter urging the home secretary, the Essex coroner and the chief coroner to ensure the inquests take place was sent.

On Tuesday, Essex county council, speaking on behalf of the Essex coroner, confirmed to the Guardian that inquests into the 39 deaths would be opened.

A spokesperson said: “When all the documentation is available, inquests touching upon the deaths of the 39 Vietnamese migrants will be opened by the Essex senior coroner.”

While criminal proceedings related to the tragic deaths continue, until now there had been no indication whether there would be any wider investigation into the circumstances surrounding the incident.

A letter from the charity Inquest, Liberty and the Joint Council for the Welfare of Immigrants had been sent to the Essex coroner, Caroline Beasley-Murray, urging her to confirm that she will hold full inquests into the deaths. It had also been sent to the chief coroner, the home secretary and Home Office ministers.

“Very serious concerns arise as to the circumstances in which 39 men, women and children came to die in such desperate circumstances in a refrigerated lorry in Essex on 23 October,” the letter states.

The three organisations question how and why the migrants came to travel undetected, particularly while crossing the border, and whether there had been a safer route for them to take. There is no legal route for unskilled workers from Vietnam to come to the UK.

“An indication from you that it is your intention that inquests should be held into these deaths would be likely to provide some welcome reassurance to the families of the deceased,” the letter says.

It adds that such confirmation would also reassure the wider public “that these deaths will be fully and fearlessly investigated in the context of widespread concern that vulnerable people are engaging in more and more desperate measures to reach the UK”.

Deborah Coles, the director Inquest, welcomed the news that inquests were to go ahead.

“We hope the scope will be broad enough to satisfy the families about how and why their loved ones died,” she said. “Vulnerable people are engaging in more and more desperate measures to reach the UK and are at risk of extreme exploitation, serious harm and death. Men, women and children died in the most shocking circumstances and we owe it to them and their families to have the most searching scrutiny of these deaths in the hope of that changes will be made to help in preventing similar future deaths.”

Pham Van Thin, the father of Pham Thi Tra My, whose text saying “I’m sorry, mum … I’m dying because I can’t breathe” was circulated around the world, said: “I hope the British government can prevent such a tragedy from being repeated and reduce the risk for all people. I support such a thorough inquest.”

Nguyen Dinh Gia, the father of Nguyen Dinh Luong, who died in the lorry, said: “We did not arrange any activities this lunar new year because we are devastated. We just stayed at home and wiped away our tears when thinking of him. Our health has worsened recently. We don’t know how we can continue to live.

“We organised the 100-day anniversary of his death on Sunday. Last year, he called us to congratulate us during lunar new year, but not this year. I agree and totally support an inquest to prevent such a case from happening again.”

A Home Office spokesperson said: “The deaths of 39 Vietnamese nationals last October was a shocking tragedy, and those responsible must be brought to justice. We are fully supporting Essex police with their investigation in this case, and are throwing the full force of the law at it.”