Germany has celebrated the 30th anniversary of the fall of the Berlin Wall that divided East and West Germany, with President Frank-Walter Steinmeier thanking Eastern European neighbours for spurring on the peaceful revolution.

Key points: Leaders from Germany, Poland, Hungary, Slovakia and the Czech Republic attended the memorial ceremony

Leaders from Germany, Poland, Hungary, Slovakia and the Czech Republic attended the memorial ceremony The German President called on Germany and its European allies to keep fighting for a peaceful and united Europe

The German President called on Germany and its European allies to keep fighting for a peaceful and united Europe German Chancellor Angela Merkel said "It teaches us: No wall that keeps people out and restricts freedom is so high or so wide that it can't be broken down"

The toppling of the wall, which separated the Communist-ruled East from the capitalist West in Berlin for nearly three decades and became a potent symbol of the Cold War, was followed a year later by the reunification of Germany in 1990.

"Together with our friends, we remember with deep gratitude the events 30 years ago," Mr Steinmeier said during a ceremony at the Bernauer Strasse Berlin Wall Memorial.

"Without the courage and the will to freedom of the Poles and Hungarians, the Czechs and Slovaks, the peaceful revolutions in Eastern Europe and Germany's reunification would not have been possible."

Leaders from Germany, Poland, Hungary, Slovakia and the Czech Republic attended the ceremony at Bernauer Strasse — where one of the last parts of the Berlin Wall remains — before placing roses in the once-fearsome barrier that divided the city for 28 years.

In August 1989, Hungarian border guards for the first time allowed people from East Germany to cross freely into Austria, paving the way for the fall of the Berlin Wall three months later and with it the end of the Iron Curtain.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 3 minutes 41 seconds 3 m 41 s The fall of the Berlin Wall explained.

Mr Steinmeier said, however, that the historic event did not mark the "end of history" as US historian Francis Fukuyama stated.

The struggle of political systems continues and the future is more uncertain than ever before, he added.

"Liberal democracy is being challenged and questioned," Mr Steinmeier said, calling on Germany and its European allies to keep fighting for a peaceful and united Europe.

"The Berlin Wall, ladies and gentlemen, is history," Angela Merkel said later at a memorial service inside a small chapel near where the Wall once stood.

"It teaches us: No wall that keeps people out and restricts freedom is so high or so wide that it can't be broken down."

"The values on which Europe is founded — freedom, democracy, equality, the rule of law, respect for human rights — are anything but self-evident.

"And they have to be filled with life and must be defended again and again," she said.

East and West Berliners meet at Potsdamer Platz after the Berlin Wall was torn down to make way for a new border crossing, on November 12, 1989. ( Reuters )

Noting the cruelty of the East German regime — which had torn down a previous church on the former "death strip" site so snipers could get a better shot at people fleeing to the West — Ms Merkel paid tribute to those who were killed or imprisoned during the Communist dictatorship and insisted that the fight for freedom worldwide was not over.

Foreign Minister Heiko Maas also used the occasion to appeal for European unity.

"Power is shifting away from Europe, authoritarian models are on the rise, the United States is increasingly looking inwards and international law is losing ground," he said.

The United States and European allies accuse Berlin of spending too little on defence, and view Germany's large current account surplus as a sign that Germans are not investing enough to support growth and development.

In a statement issued by his office, US President Donald Trump congratulated Germany on its anniversary, saying, "courageous men and women from both East and West Germany united to tear down a wall that stood as a symbol of oppression and failed socialism for more than a quarter of a century".

A big section of the Berlin Wall is lifted by a crane as East Germany starts to dismantle the wall near the Brandenburg Gate, in February 1990. ( Reuters )

"The United States and our allies and partners remain steadfast in our unwavering allegiance to advancing the principles of individual liberty and freedom that have sustained peace and spawned unparalleled prosperity," he added.

The collapse of the Berlin Wall was brought about largely by peaceful protests and a stream of people fleeing East Germany that piled pressure on the country's communist government to open its borders to the West and ultimately end the nation's post-war division.

Thirty years on, Germany has become the most powerful economic and political force on the continent, but there remain deep misgivings among some in the country about how the transition from socialism to capitalism was managed.

Ms Merkel acknowledged this in a recent interview with daily Sueddeutsche Zeitung, saying that "with some things, where one might have thought that East and West would have aligned, one can see today that it might rather take half a century or more."

Fireworks explode over Berlin's Brandenburg Gate to mark the 30th anniversary. ( Reuters: Fabrizio Bensch )

She also recalled that November 9 remains a fraught date in German history, as it also marks the anniversary of the so-called Night of Broken Glass, an anti-Jewish pogrom in 1938 that foreshadowed the Nazi's Holocaust.

Saturday's anniversary festivities in Berlin were due to culminate with a party at the Brandenburg Gate in the evening featuring the Staatskapelle Berlin orchestra directed by Daniel Barenboim and electronic music with WestBam.

Light installations, concerts and public debates were also planned throughout the city and other parts of Germany to mark the fall of the Wall.

Reuters/AP