Delegations made their way through the snow to lay candles at the Birkenau Memorial
Survivors are unlikely to gather in one place again in such numbers
Yuda Widawski, 96, is among the oldest survivors of the Auschwitz attending the ceremonies
A giant tent was erected at the Birkenau site for the commemoration
Hollywood director Steven Spielberg, who made the Holocaust film Schindler's List, was at the ceremony at Auschwitz
Dutch King Willem Alexander came for the ceremony in Poland
French President Francois Hollande (L) and Norwegian Nobel Committee Chairman Thorbjoern Jagland are at the ceremony
Auschwitz
survivors have urged the world not to allow a repeat of the crimes of
the Holocaust as they mark 70 years since the camp's liberation.
"We
survivors do not want our past to be our children's future," Roman
Kent, born in 1929, told a memorial gathering at the death camp's site
in Poland.
Some 300 Auschwitz survivors returned for the ceremony under a giant tent.
Some 1.1 million people, mostly Jews, were killed there between 1940 and 1945, when Soviet troops liberated it.
It is expected to be the last major anniversary event survivors are able to attend in considerable numbers.
Ronald
S Lauder, president of the World Jewish Congress, told the
commemoration: "Jews are targeted in Europe once again because they are
Jews...
"Once
again young Jewish boys are afraid to wear yarmulkes [skullcaps] on the
streets of Paris, Budapest, London and even Berlin."
In
the Czech capital Prague, speakers of parliament from across the EU
gathered with the European Jewish Congress to issue a declaration
condemning anti-Semitism and hate crimes.
At the scene: Kevin Connolly, BBC News
Those
who survived Auschwitz lived through one of the 20th Century's worst
acts of hatred and inhumanity. Many of those still alive today were
children in 1945 but they are elderly now and this may be the last
significant anniversary where so many will gather.
A
huge, white temporary building has been erected over the brick railway
buildings where many of the Jews of Europe were sorted into those who
were fit enough for slave labour and those who would be taken straight
to the gas chambers.
Candles
have been lit at the Death Wall where prisoners were executed - small
points of light in this wintry landscape of snow and ice, where Europe
is remembering a time of darkness.
'My mother's dream'
Welcoming the visitors, Polish President Bronislaw Komorowski said the Germans had made Poland a "cemetery for Jews".
Auschwitz survivor Halina Birenbaum, born in 1929, told the assembly that her greatest duty was to "tell others how much people [in the camps] had wanted to live".
"I lived my mother's dream to see the oppressor defeated," she said, condemning Holocaust denial and warning that anti-Semitism remained a threat.
After the speeches, Jewish and Christian prayers for the dead were said before candles were lit at the Birkenau monument to the victims.
Auschwitz was liberated on 27 January 1945. It opened as a museum in 1947.
Anniversary ceremonies took place in other parts of Europe and at Israel's Holocaust museum, Yad Vashem.
BBC