BERLIN: German President Frank-Walter Steinmeier expressed relief that Joe Biden was replacing Donald Trump as US president on Wednesday, calling it a "good day for democracy".

"I am greatly relieved that Joe Biden will be inaugurated as president today and move into the White House," the head of state said.

"I know this feeling is shared by many people in Germany."

Steinmeier said America's institutions had proven their strength in the face of "great tests" and "hostility" during Trump's term.

He said the transfer of power to Biden brought with it "the hope that the international community can work together more closely and better in future to solve the great problems of our time".

He said Germany looked forward "to knowing we again have the US at our side as an indispensable partner" in addressing "the coronavirus pandemic, climate change, security issues, arms control and disarmament, and many urgent conflicts around the world".

Even "differences of opinion" would not be allowed to "separate us, but rather lead us to look even harder for shared solutions", he added.

However Steinmeier warned that "despite the joy of this day", the last four years had shown that "populism also seduced the most powerful democracy in the world".

"We must resolutely stand up to polarisation, protect and strengthen our democracies' public sphere and make policy on the basis of reason and facts," he said.

Steinmeier extended his "best wishes" to Biden and Vice President-elect Kamala Harris "for their great and difficult tasks" ahead, saying he hoped to welcome them soon to Germany.