Holocaust survivors and members of the public will today observe a memorial day to mark the liberation of the Auschwitz-Birkenau concentration camp.
Events will be staged across the country in remembrance of victims of the Nazi persecution as well genocides in Cambodia, Rwanda, Bosnia, and Darfur.
The UK's chief rabbi Ephraim Mirvis will deliver an assembly at Copthall School in Barnet, north London, in his first address on Holocaust Memorial Day since taking up the post.
Lord Jonathan Sacks stepped down after 22 years in the role last year.
Deputy Prime Minister Nick Clegg will join survivors of the Holocaust and more recent genocides to light a candle of remembrance at King's Cross station in central London.
Prince Minister David Cameron is also staging a Downing Street reception to mark the event.
Yesterday anti-fascist protesters confronted supporters of a far-right Hungarian political party ahead of a planned rally in London.
Karen Pollock, chief executive of the Holocaust Educational Trust, said the visit of the Jobbik party leader Gabor Vona on the eve of the memorial day was "deplorable".
She said: "At a time when anti-semitic discourse is so firmly in the headlines, it is more important now than ever before for us to make a national commitment to remember the terrible events of the Holocaust."
This year's Holocaust Memorial Day marks the 69th anniversary of the liberation of Auschwitz-Birkenau, the largest Nazi death camp.