Germany marks 20 years since reunification on Sunday, an economic powerhouse and confident world player still battling to bridge enduring gaps between the west and former communist east.

“Reunified Germany has accomplished great things,” said Interior Minister Thomas de Maiziere ahead of the celebrations, adding that “people in the west and the east can be proud of what they have achieved together.”

“The whole world is amazed at us,” screamed the Bild daily recently, crowing at reunited Germany’s successes: Europe’s top economy is enjoying record growth rates, low unemployment and buoyant exports.

Meanwhile, Angela Merkel, the respected chancellor who grew up in East Germany, plays a leading role on the European and world stage, as her country lobbies for a non-permanent seat on the United Nations Security Council, following a 2003-2004 stint.

Slowly shaking off its painful history, Germany is also playing a bigger role in Afghanistan, recently conducting a raid in Baghlan billed as the first operation of its type since World War II.

“Since 1990, a great deal has been achieved in a short time,” Mr de Maiziere told reporters.

However, if outwardly the reunified Germany seems a success story that appeared far-fetched in the heady days after the Berlin Wall fell, hefty economic and social divisions remain.

Despite an estimated €1.4 trillion in transfers from west to east, the former communist part of the country continues to lag behind, with unemployment nearly twice as high and living standards much lower.

Hans-Werner Sinn, president of the influential Ifo economic institute, said: “The convergence of east Germany and west Germany is just not taking place.”

“If you want to have convergence and you are behind, then you need to run faster and they (the east Germans) haven’t done this.”

Mr Sinn estimated east Germany’s output per capita, a commonly used measure of living standards, is 65.8 per cent that of the west.

Not one of Germany’s top 30 companies has headquarters in the east and a recent study for IW Consult ranked six east German states in the bottom seven for economic development.

Adding to its plight, nearly three million have left east Germany since reunification as people search for work on the other side of the former border.

While it is not all doom and gloom – living standards have improved since 1990 and unemployment is much lower – one recent survey showed less than half of all Germans (46 per cent) saw reunification as positive.

Matthias Platzeck, the state premier of Brandenburg to the region surrounding Berlin which used to belong to East Germany, caused uproar last month when he spoke of the “annexation” or “Anschluss” of the east by the west.

Reunification marked the beginning of the “de-industrialisation of east Germany”, he told Spiegel magazine, adding: “For many of us, this day isn’t just one of good thoughts.

“I don’t know what there is to celebrate.”

Hans-Dietrich Genscher, a former West German foreign minister who shares credit for bringing about reunification, said some progress had been made but plenty remained to be done.

“We are over the hump but not yet there. You can’t change 40 years of communist government overnight and we have already achieved a lot. We said it would be a long and rocky road,” he told reporters.

Others were more pessimistic. Asked how long it would take before the east finally catches up, Ifo’s Mr Sinn said: “I don’t see the prospect of that happening. It will be a backward region for a long period ahead.”