World leaders congratulate US President Biden

World leaders said they were looking forward to working with Joe Biden, as the Democrat was sworn in as US president after four turbulent years under Donald Trump.

Charles Michel, president of the European Council, tweeted congratulations to both Biden and Vice President Kamala Harris, adding: "It's time to bring back conviction & common sense and rejuvenate our EU-US relationship."

European Commission President Ursula von der Leyen said: "Europe is ready for a fresh start."

President Hassan Rouhani hailed the departure of "tyrant" Trump, Tehran having repeatedly called on Washington to lift sanctions imposed over its nuclear drive.

"We expect (the Biden administration) to return to law and to commitments, and try in the next four years, if they can, to remove the stains of the past four years," said Rouhani.

Biden's administration wants the United States back in the landmark Iran nuclear accord, from which Trump withdrew, provided Tehran returns to strict compliance.

Prime Minister Benjamin Netanyahu urged Biden to "strengthen," a long-standing alliance between the two countries.

"I look forward to working with you to further strengthen the US-Israel alliance, to continue expanding peace between Israel and the Arab world and to confront common challenges, chief among them the threat posed by Iran," Netanyahu said in a video.

"The bond between North America and Europe is the bedrock of our security, and a strong NATO is good for both North America and Europe," said NATO General Secretary Jens Stoltenberg.

"NATO Allies need to stand together to address the security consequences of the rise of China, the threat of terrorism, including in Afghanistan and Iraq, and a more assertive Russia."

Pope Francis urged Biden to promote "reconciliation and peace" around the world.

"At a time when the grave crises facing our human family call for far-sighted and united responses, I pray that your decisions will be guided by a concern for building a society marked by authentic justice and freedom," the pope said.

Kremlin spokesman Dmitry Peskov said Russia would seek "good relations with the United States", while a foreign ministry statement said they expected a "more constructive" approach to upcoming arms control talks.

The US and Russia are to discuss extending the landmark 2010 New START nuclear weapons accord shortly after Biden's swearing in. The last remaining nuclear pact between the countries, it limits each side to 1,500 nuclear warheads and is set to expire February 5.

President Frank-Walter Steinmeier of Germany, Europe's biggest economy, said he was "greatly relieved" Biden was replacing Trump as US president, calling it a "good day for democracy".

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".

French government spokesman Gabriel Attal said Biden's commitments to rejoin the World Health Organization, which leads the global response to the Covid-19 pandemic, and the Paris climate treaty were "extremely important" following Trump's exit from them.

Prime Minister Boris Johnson, who has faced criticism over his close relationship with Trump, said he was looking forward to "working closely" with Biden.

"In our fight against Covid and across climate change, defence, security and in promoting and defending democracy, our goals are the same and our nations will work hand in hand to achieve them," he said.

"Today a true friend of Ireland @JoeBiden became the 46th President of the USA," Prime Minister Micheal Martin wrote on Twitter.

"It is a day of history and hope and I look forward to forging ever closer ties between our two great nations."

"Our two countries are more than neighbours - we are close friends, partners, and allies," Prime Minister Justin Trudeau said, pledging Canada's cooperation in fighting the coronavirus pandemic, for climate action and for a sustainable economic recovery.

Indian Prime Minister Narenda Modi tweeted: "My warmest congratulations to @JoeBiden on his assumption of office as President of the United States of America. I look forward to working with him to strengthen India-US strategic partnership."