Diplomats past and present in Singapore paid tribute and praised former United Nations Secretary-General and Nobel Peace Prize laureate Kofi Annan, who died yesterday at the age of 80.

Emeritus Senior Minister Goh Chok Tong, who worked with Mr Annan when he was serving as Singapore's prime minister, told The Sunday Times that the Ghanaian was a wise and thoughtful leader who brought grace, humility and dignity" to the office of the UN Secretary-General.

"The world has lost an iconic leader and a wonderful human being," he added.

Mr Annan died in hospital in Bern, Switzerland, in the early hours yesterday, his close associates said. In Geneva, the Kofi Annan Foundation announced his peaceful death after a short undisclosed illness with "immense sadness", Reuters reported.

After rising through the ranks of the UN, Mr Annan served two terms as UN secretary-general in New York from 1997 to 2006 and retired to live in a Swiss village.

He and the United Nations shared the 2001 Nobel Peace Prize for efforts to reform the world body and give priority to human rights issues.

Singapore's Ambassador-at-Large Tommy Koh and veteran diplomat Chan Heng Chee said that Mr Annan was an outstanding and highly respected UN secretary-general, who had the courage to describe the United States-led Iraq War as illegal under international law. "I salute him, because he tried his best to bring peace to this troubled world and because he was a kind and gentle man," Professor Koh said.

Mr Annan also understood that for the UN to succeed, he had to get the support of not just governments but also the common people, said former senior diplomat Kishore Mahbubani, who knew him for more than 30 years.

Social scientist Noeleen Heyzer, a former undersecretary-general of the UN, said that at a time when the world is faced with multiple wars, massive displacement, growing xenophobia and a backsliding of democratic principles, "Mr Annan's noble life and legacy will remain a guiding light for all of humanity".