Kofi Annan, the Ghanaian who led the United Nations as Secretary-General through tumultuous years that included the first Gulf War, has died at the age of 80.

The Nobel Peace Prize laureate passed away in Bern, Switzerland, in the early hours of Saturday, two of his close associates said.

In Geneva, the Kofi Annan Foundation announced his peaceful death with “immense sadness” after a short illness, saying he was surrounded in his last days by his second wife, Nane, and children Ama, Kojo and Nina.

Annan served two terms as UN Secretary-General in New York from 1997 until 2006 and retired first to Geneva and later to a Swiss village in the nearby countryside.

“In many ways, Kofi Annan was the United Nations,”  UN Secretary-General Antonio Guterres, whom Annan had chosen to head the UN refugee agency, said in a statement.

“He rose through the ranks to lead the organisation into the new millennium with matchless dignity and determination.”

His tenure at the upper levels of the world body was not without controversy.

In 1995 he was widely criticised for failing to immediately investigate the circumstances under which a lucrative contract was awarded to an African company that had hired his son, Kojo.

That scandal saw the New York Times criticise Annan in an editorial that accused him of “a grievous lapse, for which the United Nations is now paying the price as critics accuse it of conflicts of interest and corruption in high places.”

Nor was it the only scandal involving his son to cast a shadow over Annan’s stewardship of the UN and its reputation.

In another damaging episode, Kojo Annan admitted trading on his father’s diplomatic influence and contacts to dodge some $8000 in tariffs when importing a top of the line Mercedes to Ghana.

As head of UN peacekeeping operations, Annan also was criticised for the world body’s failure to halt the genocide in Rwanda in the 1990s.

“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’s Hard Talk during an interview for his 80th birthday last April, recorded at the Geneva Graduate Institute where he had studied.

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

-with AAP