Those who provide you with clear and honest information are our best allies Kofi Annan

He said that for many people, "the BBC World Service has been a lifeline - to learning, to enlightenment, to hope itself".

His full speech was broadcast on BBC World Service outlets.

'Knowledge is power'

Mr Annan said that long before the internet arrived, BBC radio had connected the world, providing everything from the latest cricket scores to impartial analysis on news events.

He underlined the importance of all societies having access to the kind of information they needed to build better lives.

Mr Annan said the World Service had led to enlightenment and hope

"It is an old saying that knowledge means power," Mr Annan said.

The UN, he said, had a role in keeping people informed - but so too did the World Service.

"The better informed you are, the greater our chances of success. And those who provide you with clear and honest information are our best allies," he said.

Personal memories

He spoke of his own memories of growing up with the World Service.

Mr Annan used his lecture to say war in Iraq could still be avoided

"I remember, growing up in Ghana during the struggle for independence... the suspenseful silence that would descend on parents and professors alike at the approach of the latest headlines," he said.

Mr Annan also used the lecture to speak of the growing disparities between the world's peoples - disparities of wealth, freedom and privilege.

"At the dawn of the 21st century we face a strange paradox," he said. "The more we know about the issues, and about each other, the more we act as if we were strangers."

Message to Iraq

Mr Annan also used his speech to send a message to potential listeners in Iraq regarding the current UN weapons inspections.

"A peaceful resolution is possible, if your government complies fully with its obligations under Security Council resolutions," he said.

But he said it was essential the weapons inspectors completed their task.

"I would be deceiving you if I were to suggest otherwise," he said.

Mr Annan also stressed that Iraq could not hope to see the lifting of UN sanctions for as long as it retained weapons of mass destruction.