It was the first funeral service in Britain for victims of the Holocaust. Around 50 Holocaust survivors were in attendance. They were joined by relatives of survivors. Many of the people at the service were moved to tears.
The ashes and bones of the six unknown victims were sent from Auschwitz to the Imperial War Museum in London in 1997.
Scientific tests later discovered they were five adults and one child, but nothing else is known about who they were.
They were laid to rest at the United Synagogue New Cemetery in Bushey, on the northwest edge of London. A small coffin containing all the remains was buried with earth from Israel.
Chief Rabbi Ephraim Mirvis addressed the unknown victims during the service. He also reflected on the wider issue of anti-Semitism in society.
“The message that you convey through the presence of your remains before us today is that if anti-Semitism exists, and it goes by unchecked, then hate speech can easily be translated into hate crime,” said Chief Rabbi Ephraim
“And when anti-Semitism is allowed to thrive, some people can do anything and some people can reach the lowest end of human conduct.”
He had previously said he hoped the site could become a place of pilgrimage for Jewish families.
Britain's communities minister James Brokenshire, Israeli ambassador Mark Regev and Queen Elizabeth II's representative in the local county were in attendance.
A memorial garden is set to be established on the site.
SEE ALSO: Record numbers visit Auschwitz in 2018
At least six million Jews were murdered by the Nazis and their allies during World War Two,
Many were starved and gassed to death, and their remains incinerated, including more than a million men, women and children who were murdered in the Auschwitz death camp in German-occupied Poland.