The opening ceremony in the renovated Reichstag building marked the 50th anniversary of its first post-war session.

In his opening address, parliament president Wolfgang Thierse, a former East German dissident, said that respect for peace, justice and solidarity were stronger in the west than the former communist east.

Ten years after the fall of the Eastern Bloc, the region is still battling against the social and economic ramifications of unification.

Rise of extremists

The warning came just two days after an extreme-right party won seats for the first time in the legislature of the eastern state of Brandenburg, the Prussian heartland which surrounds Berlin.

Renovation by architect Sir Norman Foster took 4 years and cost $11bn

The victory heightened concerns that the German People's Party, already represented in the Saxony-Anhalt legislature, would win seats in the Thuringia parliament during state elections on Sunday.

"The democratisation of West Germany went since 1949 with growing prosperity and gradual full employment," said Mr Thierse.

"In East Germany, great unemployment has reigned for the past 10 years. So it would therefore be too much probably to expect the same excitement for democracy from the East Germans that has grown over 50 years in West Germany.

"Here, the parliament must first prove itself."

The ceremony was the first time parliament met since it began its summer break in July to begin the move from the west German capital of Bonn back to Berlin, Germany's historic seat of power.