any "organised crime groups who may have played a part".

Video caption Essex lorry deaths: CCTV shows arrival at industrial park

A spokesman for the Bulgarian foreign affairs ministry said the truck was registered in the country under the name of a company owned by an Irish citizen.

He said it was "highly unlikely" the deceased were Bulgarians.

Image copyright PA Media Image caption The lorry has been moved to a secure location at Tilbury Docks

At the scene

By Ed Thomas, special correspondent, BBC News, Grays

Police officers bowed their heads in silence as the lorry was slowly moved from the industrial estate with all 39 people still inside the container.

I've seen senior detectives visibly upset at what they've witnessed here.

Detectives said their priority now was providing all the victims with dignity and respectas they try to identify them and inform their loved ones.

Prime Minister Boris Johnson said it was an "unimaginable tragedy and truly heartbreaking".

Speaking at Prime Minister's Questions, he said: "I know that the thoughts and prayers of all members will be with those who lost their lives and their loved ones.

"I'm receiving regular updates. The Home Office will work closely with Essex Police as we establish exactly what has happened."

During Thurrock Council's full council meeting, councillor James Halden said the authority would put in place any support enforcement agencies needed.

The Conservative councillor urged people not to speculate about what may have happened and said there was a book of condolences for members of the public to sign in the civic offices.

Tricky task of catching the people smugglers

Since the