The BBC's James Robbins: "His strengths were also his weakness"

The death of the 77-year-old statesman, who led his country to independence, was announced on Tanzanian radio by the current Head of State, Benjamin Mkapa.

Dr Nyerere had been diagnosed with leukaemia in August and was admitted to St Thomas' hospital in London three weeks ago.

In Tanzania, 30 days of mourning have been declared for the man known affectionately as "Mwalimu" - Kiswahili for "the teacher".

Flags are flying at half-mast and many radio and television stations have been playing religious music.

President Mkapa said arrangements were being made for a state funeral.

In New York, the United Nations General Assembly stood in silent tribute to Dr Nyerere.

The President of the Assembly, Namibian Foreign Minister Theo-Ben Gurirab, called him "a venerable world leader and one of Africa's most charismatic and respected elder statesmen".

He recalled how Dr Nyerere had given refuge to the many black nationalist leaders who fled South Africa under apartheid. They were allowed to set up training camps inside Tanzania.

In Addis Ababa, the Secretary-General of the Organisation of African Unity, Salim Ahmed Salim, called the former president's death "a severe and painful personal loss".

Dr Nyerere was one of the founding members of the OAU and a passionate believer in the cause of pan-Africanism.

South African President Thabo Mbeki: "A loss for Africa as a whole"

South African President Thabo Mbeki said Dr Nyerere "served as a source of great inspiration to efforts towards Africa's rebirth".

"He was one of the wise sons of Africa who guided our journey towards placing Africa in her rightful place in the world," he said.

The Zambian President, Frederick Chiluba, said it was a sad day for Africa.

"We have lost a champion and great leader," he said.

Revolutionary and visionary

In Kenya, President Moi said Dr Nyerere was "a good friend" and that Kenyan flags would fly at half-mast for four days in tribute.

Robert Mugabe, president of Zimbabwe, said Dr Nyerere had been "the revolutionary, the visionary, the principled, indomitable and unyielding support of the struggle for our own and the region's independence".

Julius Nyerere talking to the BBC in 1975, defending his own vision of democracy

UK Prime Minister, Tony Blair, led tributes from Europe saying: "The fact that Tanzania is today a country at peace with itself and its neighbours is, in large part, a tribute to Mwalimu."

Julius Nyerere served as Tanzania's first president from 1961 to 1985.

Addressing the nation on television, Tanzanian President Mkapa said the challenge now was for Tanzanians to build on the important foundation which he laid for the nation.

An important opponent of colonialism and apartheid, Dr Nyerere stood out as an African leader who ignored the trappings of power.

Listen to the announcement of Julius Nyerere's death (in Swahili)

But while he united his nation and made major advances in the fields of health and education, his African socialist policy of "ujama" - community-based farming collectives - proved disastrous for Tanzania's economy.

After stepping down as president, Dr Nyerere became an influential figure on the international scene, becoming one of Africa's most respected elder statesmen.

Most recently, he had been mediating talks in northern Tanzania aimed at ending the ethnic and political conflict in Burundi.