The government is working on attracting foreign workers to "keep the show on the road" despite an ageing population, making an estimated 7% rise in population to 90 million by 2070 plausible, Scholz told a citizen forum in Potsdam, near Berlin.

The German government last month agreed plans to reform immigration law, as Berlin seeks to open up the job market in Europe's biggest economy to much-needed workers from outside the European Union.

The government has said it wants to boost immigration and training to tackle a skills shortage weighing on the German economy at a time of weakening growth, with an aging population piling pressure on the public pension system.

Scholz said that current population growth due in part to rising immigration meant the government might not to raise pension contributions before the end of its mandate in 2025.

Germany's statistics office said last week the population would likely rise by 1 million to 84 million this year due to migration from Ukraine. It could reach 90 million in coming decades, if immigration was high, it added.