Germany on Monday celebrated the 21st anniversary of its 1990 reunification, as Chancellor Angela Merkel, President Christian Wulff and other political leaders gathered in the former West German capital, Bonn.

West Germany and communist East Germany were reunited on Oct. 3, 1990, less than 11 months after the Berlin Wall was torn down.

Germany has the European Union's biggest economy and is a key player in the attempt to get the eurozone's debt crisis under control.

Earlier in the day, German authorities released four men arrested on Saturday on suspicion of planning attacks at celebrations marking Unity Day. A police spokesman said the state prosecutor ruled there was not enough concrete evidence that the men were linked to terror groups or had been planning attacks.