Kofi Annan, the former UN secretary-general, has died aged 80.

The Ghanaian national was the first black African to be appointed as the world’s top diplomat and was awarded the Nobel Peace Prize for his humanitarian work during his eight years in the role.

He died in hospital in Bern, Switzerland, in the early hours of Saturday morning.

His death was announced by his family and the Kofi Annan Foundation, which said he had “passed away peacefully” following a short illness.

Mr Annan’s second wife Nane and children Ama, Kojo and Nina were by his side during his last days, they added.

In a statement, the foundation said: “Kofi Annan was a global statesman and a deeply committed internationalist who fought throughout his life for a fairer and more peaceful world.

“Wherever there was suffering or need, he reached out and touched many people with his deep compassion and empathy. He selflessly placed others first, radiating genuine kindness, warmth and brilliance in all he did.”

Kofi Annan – Former UN secretary-general in pictures Show all 30 1 /30 Kofi Annan – Former UN secretary-general in pictures Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2005 Kofi Annan addresses the United Nations General Assembly to unveil his blueprint for the most sweeping changes to the United Nations and the International system of security since World War II, at United Nations Headquarters in New York EPA Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 1960s Kofi Annan breaking 12 year record for the 60 yards sprint at Carleton Stadium at Macalester College, Minnesota EPA/United Nations Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 1960s Kofi Annan showing his Kente robe to fellow students on International Students Day, during his younger years EPA/United Nations Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 1971 Kofi Annan with fellow students as an MIT Sloan Fellow, studying copper industry, in Zambia EPA Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 1997 Pope John Paul II speaks with Kofi Annan during a private audience at the Vatican REUTERS Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 1997 United Nations Secretary General Kofi Annan with his wife Nane, as they tour the Great Wall of China during a five-day visit AP Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 1997 Chinese President Jiang Zemin, left, greets visiting UN Secretary-General Kofi Annan at Zhongnanhai, the official compound of the Chinese leadership AP Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 1997 Kofi Annan, centre, inspects the Swedish army base SWEDINT, south of Stockholm, with Swedish defense minister, Bjoern von Sydow, left. A training camp for Swedish UN soldiers AP//United Nations Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 1997 Kofi Annan speaks at the White House after meeting President Clinton Reuters Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 1997 Opera great Luciano Pavarotti, left, pays a courtesy visit to Kofi Annan AP Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 1998 Kofi Annan walks by skulls at the Mulire Genocide memorial AFP/Getty Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2000 Palestinian President Yasser Arafat walks with Kofi Annan after they concluded talks in Gaza Reuters Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2000 Cuban President Fidel Castro. left, and General Secretary of the United Nations Kofi Annan review a guard of honor upon Annan's arrival in Havana AFP/Getty Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2000 Kofi Annan consoles family members of the victims of the massacre by pro-Indonesia militia in Liquisa Reuters Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2003 Kofi Annan greets President Bush at UN headquarters before the start of the 58th UN General Assembly AP Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2005 Kofi Annan arrives with "Make Poverty History" organiser Bob Geldof and U2 lead singer Bono for a session of the G8 summit in Gleneagles, Scotland Reuters Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2006 Kofi Annan receives an honorary Doctor of Public Service degree at George Washington University in Washington AFP/Getty Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2006 Kofi Annan (upper-L) waves as he receives a standing ovation following his speech to the 61st session of the United Nations General Assembly AFP/Getty Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2006 Kofi Annan and his wife Nane Lagergren pose with the 2006 Geneva Foundation Prize EPA Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2007 Nelson Mandela and Kofi Annan arrive together at the 5th Nelson Mandela Annual Lecture held at the Linder Auditorium in Johannesburg AP Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2007 Kofi Annan displays a AK47 gun transformed to a guitar at Vienna's UN headquarters Reuters Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2007 Kofi Annan during a meeting with Queen Elizabeth II at Buckingham Palece PA Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2012 Russian President Vladimir Putin, right, shakes hands with United Nations special envoy Kofi Annan in Moscow AP Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2012 UN-Arab League envoy Kofi Annan speaks during a news conference in Damascus Reuters Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2012 Syria's President Bashar al-Assad meets UN Syria peace envoy Kofi Annan in Damascus SANA/Reuters Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2012 Kofi Annan looks on before a meeting at his office at the United Nations Offices in Geneva AFP/Getty Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2013 Kofi Annan and his wife Maria Annan arrive to attend a dinner hosted by Queen Beatrix of The Netherlands ahead of her abdication at Rijksmuseum in Amsterdam Getty Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2016 Kofi Annan listens to a Rohingya religious and community leader in the Internally Displaced People's camps during a visit by the Rakhine Advisory Commission in Thetkabyin village, outside Sittwe, the capital of Rakhine state in Myanmar AP Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2016 Kofi Annan delivers his address while Myanmar State Counsellor and Foreign Minister Aung San Suu Kyi listens during their meeting at the National Reconciliation and Peace Centre in Yangon with the multi sector advisory body to find lasting solution to Myanmar's stateless Rohingya Muslims AFP/Getty Kofi Annan – Former UN secretary-general in pictures Kofi Annan – 2001 Kofi Annan and President of the UN General Assembly Han Seung-soo present their Nobel Peace Prize Awards EPA

Mr Annan devoted virtually his entire career to the UN, where he served two terms as secretary-general between January 1997 and December 2006.

His tenure was capped by winning the Nobel Peace Prize, awarded jointly to Mr Annan and the UN in 2001 for “their work for a better organised and more peaceful world”.

“In many ways, Kofi Annan was the United Nations. He rose through the ranks to lead the organisation into the new millennium with matchless dignity and determination,” said current UN secretary-general Antonio Guterres, who described his predecessor as “a guiding force for good”.

“It is with profound sadness that I learned of his passing,” Mr Guterres added.

Tributes poured in from world leaders after news of Mr Annan’s death emerged.

Former British prime minister Tony Blair, with whom the UN chief clashed over the Iraq war, said Mr Annan was “a great diplomat, a true statesman and a wonderful colleague.

Theresa May lauded “a great leader and reformer of the UN” who “made a huge contribution to making the world he has left a better place than the one he was born into”.

Mr Annan faced one of the most turbulent periods in the UN’s history during his time as secretary-general. He took on the post six years after the collapse of the Soviet Union and presided over an era marked by the 9/11 attacks and dominated by the subsequent “war on terror”.

Kofi Annan, here with former American president George W Bush, was an outspoken critic of the US-led war on Iraq (AP)

His relationship with the US tested him as a diplomatic leader amid deep global divisions over the Iraq war.

In 2013, he told Time magazine the UN’s inability to stop the Iraq war was his “darkest moment”.

“I worked very hard – I was working the phone, talking to leaders around the world,” he recalled. ”The US did not have the support in the Security Council. So they decided to go without the council. But I think the council was right in not sanctioning the war. Could you imagine if the UN had endorsed the war in Iraq, what our reputation would be like?

“At that point, President [George W] Bush said the UN was headed toward irrelevance, because we had not supported the war. But now we know better.”

Responding to Mr Annan’s death on Saturday, Mr Bush said: “Kofi was a gentle man and a tireless leader of the United Nations. His voice of experience will be missed around the world.”

Much of Mr Annan’s second term was spent at odds with the US, the UN’s biggest contributor, as he leaned on the nation to pay almost $2bn (£1.56bn) in arrears.

He was not immune to criticism; as head of UN peacekeeping operations, Mr Annan came under fire for the world body’s failure to halt the Rwandan genocide in the 1990s.

Challenges from the outset forced him to spend much of his time as secretary-general struggling to restore the UN’s tarnished reputation.

His enduring moral prestige remained largely undented, however, and his cool-tempered elegance and political savvy helped guide him an unprecedented uncontested second term as secretary-general.

When he departed the UN, he left behind a global organisation more aggressively engaged in peacekeeping and fighting poverty, setting the framework for the organisation’s 21st century response to mass atrocities and its emphasis on human rights and development.

“The UN can be improved, it is not perfect, but if it didn’t exist you would have to create it,” he told the BBC world news programme Hard Talk during an interview for his 80th birthday last April.

“I am a stubborn optimist, I was born an optimist and will remain an optimist,” Mr Annan said.

Kofi Annan walks by skulls at a memorial to the Rwandan genocide, which the UN faced criticism for failing to halt (AFP/Getty Images)

Even after his tenure ended, Mr Annan never completely left the UN orbit. He returned in special roles, including as the UN-Arab League’s special envoy to Syria in 2012.

He remained a powerful advocate for global causes through his eponymous foundation.

UN high commissioner for human rights Zeid Ra’ad al-Hussein, paid tribute to Annan as “humanity’s best example, the epitome, of human decency and grace”.

Mr Zeid, who has criticised major powers during his four-year term, said that whenever he felt “isolated and alone politically” he would go for long walks with Mr Annan in Geneva.

He added: “When I told him once how everyone was grumbling about me, he looked at me – like a father would look at a son – and said sternly: ‘You’re doing the right thing, let them grumble.’”

Former UK prime minister Gordon Brown, who is currently the UN special envoy for global education, said Mr Annan was “a leader of leaders, a wonderful humanitarian and the most compassionate and caring of individuals”.

“Personally modest and always softly spoken, he was a titan amongst world statesman who saw wrong and righted it and who witnessed evil and always fought it,” he added.

“Even in his later years he fought against poverty, injustice and war with all the vigour of youth and I had the privilege of working with him in recent times.”

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Former US president Barack Obama said Mr Annan “embodied the mission of the United Nations like few others”.

“His integrity, persistence, optimism, and sense of our common humanity always informed his outreach to the community of nations,” he added. ”Long after he had broken barriers, Kofi never stopped his pursuit of a better world, and made time to motivate and inspire the next generation of leaders.”

The Elders, an elite group of former leaders founded by Nelson Mandela and chaired by Mr Annan, said they were “shocked and deeply saddened” by his death.

In a statement, they described him as “a voice of great authority and wisdom in public and private”.

“His quiet advice on how best to defuse impending crises was in constant demand from all corners of the globe, in particular from Africa,” said deputy chair Gro Harlem Brundtland, the former Norwegian prime minister.

Vladimir Putin paid tribute to a “remarkable person and great politician”.

“I sincerely admired his wisdom and courage, his ability to make balanced decisions even in the most difficult, critical situations,” the Russian president added.