German Chancellor Angela Merkel and President Joachim Gauck joined hundreds of other invited guests as the festivities in Hanover began with an ecumenical service at the city's central Marktkirche church.

For the first time on the national holiday, representatives of Germany's Jewish and Muslim communities joined their Christian counterparts in addressing the congregation with messages of peace.

Lutheran Bishop Ralf Meister used his remarks to highlight the plight of civilians caught up in the fighting in Syria and northern Iraq, where Islamist militants have taken control of large swathes of territory in recent months.

"It is with despair that we observe persecution, expulsion and unbelievable brutality," he said.

Bishop Meister also alluded to the tens of thousands who have tried to reach the safety of the European Union by crossing the Mediterranean Sea in often unseaworthy vessels - and despite the efforts of EU member states to tighten up their outer borders.

"Europe's humanity is being cast away in the Mediterranean," Meister said.

Following the service, Merkel and Gauck were to join more than 1,000 invited guests at the larger main national holiday ceremony in Hanover.

Each year a different major city hosts the main celebrations to mark Germany's national holiday, which falls on the anniversary of the reunification of the former West and East Germany on October 3, 1990.

2014 also marks the 25th anniversary of the fall of the Berlin Wall in November of 1989, which marked a major step towards the fall of communism in most of the-then eastern Soviet bloc and, almost a year later, Germany's reunification.

pfd/ipj (dpa, EPD)