South Africa has thrown a spectacular welcoming ceremony for delegates to the World Summit on Sustainable Development in Johannesburg.

Amid displays of African dance and a firework display, President Thabo Mbeki urged delegates to go into the summit on Monday in a mood of hope, not despair.

The spectacular ceremony went off in a carnival atmosphere

But major divisions have already emerged in discussions between rich and poor nations ahead of the 10-day event.

The summit's aim is to reach agreement on reducing poverty in developing nations by fuelling environmentally-friendly economic growth.

"Out of Johannesburg and out of Africa must emerge something new that takes the world forward away from the entrenchment of global apartheid to the realisation of goals of sustainable development," said Mr Mbeki at the welcoming ceremony at the Ubuntu (Friendship) Village venue.

"This is a moment of hope, not despair."

Gloom

Many delegates have voiced pessimism about the prospects for reaching consensus on how to save the global environment and tackle poverty.

The BBC's Elizabeth Blunt, in Johannesburg, says delegates will start their meetings with about three-quarters of the final declaration already agreed.

I think it's looking like we're going to get a pretty modest set of outcomes

Tony Juniper, Friends of the Earth International

The remaining 25% includes contentious issues such as the view to be taken on globalisation and world trade, and the extent to which countries bind themselves to dated targets.

Disagreements at the pre-summit informal talks are reported to have centred on the linking of aid to democratic reforms and farm subsidies.

The South African Deputy Foreign Minister, Aziz Pahad, said it was "romantic to assume that there would be absolute consensus at such a huge, diverse conference".

Key summit issues

Financing of development Fair access to markets Reversing environmental degradation Access to water and sanitation Sharing renewable energy sources

Compromises on key issues such as boosting healthcare, curbing pollution from fossil fuels and preserving dwindling fish stocks might have to be deferred until world leaders meet on the final two days, delegates said.

More than 100 heads of state accompanied by 40,000 officials are expected to attend the summit.

However, President George W Bush of the US - the world's largest economy and biggest polluter - will not be there.

Trade disputes

Poor nations want more aid and better access to the markets of wealthy nations, but developed countries are concerned about the potential impact on their economies.

Access to water is proving a contentious issue

"I think it's looking like we're going to get a pretty modest set of outcomes," said Tony Juniper, vice chairman of Friends of the Earth International.

"It's clear that we're going to get no legally binding targets."

Some protesters have threatened to try to disrupt the proceedings.

Saturday saw police in Johannesburg fire stun grenades at a group of several hundred demonstrators.

The summit follows up a meeting in Rio de Janeiro a decade ago that set goals for protecting the planet, ranging from curbing emissions of the polluting gases blamed for global warming to preventing the spread of deserts.

United Nations Secretary General Kofi Annan says progress since Rio has been "far from satisfactory".

'Illegal' march

About 10,000 extra police and troops are on duty for the summit.

On Saturday night, several hundred people defied a police ban and tried to march in central Johannesburg.

The marchers were chanting slogans against globalisation, the summit and the South African Government.

Police fired stun grenades to disperse the crowd. One man was arrested.

According to South African law, demonstrators must obtain permission to take part in a legal march.