Leaders at the world development summit in Johannesburg have warned of a dangerous future for the planet unless decisive action is taken to tackle poverty and protect the environment.

"Our house is burning down and we're blind to it," French President Jacques Chirac told the more than 100 world leaders gathered for the final three days of the summit.

We here in southern Africa have one big problem, created by the British

Sam Nujoma, Namibian president

Earlier, South African President Thabo Mbeki opened the final phase of the 10-day meeting, calling on delegates to "set concrete goals and targets" to help developing countries.

As heads of state took turns to speak, their ministers resumed negotiations to try to reach a final declaration by the official end of the summit on Wednesday.

After a week of tough talking, agreement has been struck on all but one main issue - a timetable for increasing the use of renewable energy, such as wind and solar power.

The United States, Japan and many developing countries oppose setting such targets.

• UN Secretary General Kofi Annan said the race for growth was leading mankind down a "dead end" and urged rich countries to lead the way towards saving the planet.
• UK Prime Minister Tony Blair called for the industrialised world to open its markets to developing countries, particularly in agriculture.
• German Chancellor Gerhard Schroeder urged all countries to ratify the Kyoto Protocol on global warming so that it can be implemented by the end of this year.
• Canadian Prime Minister Jean Chretien said Canada would vote on ratifying the protocol by the end of 2002.

In the conference hall, the President of Namibia, Sam Nujoma, broke ranks and used the event to criticise the European Union.

Mr Nujoma, an ally of Zimbabwe, accused Britain of creating one of the biggest problems in the region.

"We here in southern Africa have one big problem, created by the British. The honourable [UK Prime Minister] Tony Blair is here, and he created the situation in Zimbabwe," Mr Nujoma told the session.

Mr Mugabe, who left the hall during speeches by Mr Blair and the president of the European Commission, took the floor on Monday afternoon.

As well as the dispute over renewable energy, discussions are also stuck on a clause in the draft document referring to the provision of health services.

'Needless suffering'

Mr Mbeki said that although illness, poverty and conflict were prevalent around the globe, the means to solve the world's problems already existed.

Annan urged rich countries to lead the way

"Why do millions die every year from avoidable and curable diseases when sciences, technology and engineering have the means to save these human lives? Why do we have wars when we established institutions to end war?" he asked.

"The matter rests with all of us gathered here," he said, adding, "Nothing whatsoever can justify any failure on our part to respond to this expectation."

His words were echoed by UN Secretary General Kofi Annan, who called on rich countries to "lead the way" towards saving the planet.

"They have the wealth, they have the technology and they contribute - disproportionately - to global environmental problems," he said.

Poverty... deprives the whole world of the benefits of the talents of poor nations

Tony Blair, UK prime minister

The secretary general said current methods of production which damage the environment and leave humans suffering had to be revised before they "prove to be a dead-end road for everyone".

The UK prime minister urged all countries to ratify the Kyoto agreement on climate change, warning that the world would face "catastrophe" if it failed to act.

He also called on developed countries to open their markets - particularly agriculture - to developing countries.

"Poverty damages the poor most but it also deprives the whole world of the benefits of the talents of poor nations and their people," he said.

US President George W Bush will not attend the summit, leaving Secretary of State Colin Powell to take his place.

Organisers had hoped that a complete package would be agreed before the leaders started addressing the summit.

Environmentalists say that compromises so far have softened the final version of the document.

The eventual plan, which will be non-binding, will set the environmental agenda for the next 10 years.